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  • 1.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ab initio modeling of materials relevant for modern energy technologies2008Inngår i: Joint ICTP-IAEA Workshop on the Training in Basic Radiation Materials Science and its Applications to Radiation Effects Studies and Development of Advanced Radiation-Resistant Materials,2008, Italy: Italy , 2008Konferansepaper (Fagfellevurdert)
  • 2.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Magneto-structural coupling in itinerant systems2008Inngår i: International Workshop on Ab initio Description of Iron and Steel: Magnetism and Phase Diagrams ADIS08,2008, Germany: Garmany , 2008Konferansepaper (Fagfellevurdert)
  • 3.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Phase stability and structural characterization of surface and thin film alloys2008Inngår i: 12th International Conference on Theoretical Aspects of Catalysis ICTAC-12,2008, Bulgaria: Bulgaria , 2008Konferansepaper (Fagfellevurdert)
  • 4.
    Abrikosov, Igor A.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Steneteg, Peter
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Hultberg, Lasse
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Hellman, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Yu Mosyagin, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Moscow, Russia.
    Lugovskoy, Andrey V.
    Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Russia.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia; Department of Physics and Engineering, Tomsk State University, Tomsk, Russia.
    Finite Temperature, Magnetic, and Many-Body Effects in Ab Initio Simulations of Alloy Thermodynamics2013Inngår i: TMS2013 Supplemental Proceedings, John Wiley & Sons, 2013, s. 617-626Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Ab initio electronic structure theory is known as a useful tool for prediction of materials properties. However, majority of simulations still deal with calculations in the framework of density functional theory with local or semi-local functionals carried out at zero temperature. We present new methodological solution.s, which go beyond this approach and explicitly take finite temperature, magnetic, and many-body effects into account. Considering Ti-based alloys, we discuss !imitations of the quasiharmonic approximation for the treatment of lattice vibrations, and present an accurate and easily extendable method to calculate free ,energies of strongly anharmonic solids. We underline the necessity to going beyond the state-of-the-art techniques for the determination of effective cluster interactions in systems exhibiting mctal-to-insulator transition, and describe a unified cluster expansion approach developed for this class of materials. Finally, we outline a first-principles method, disordered local moments molecular dynamics, for calculations of thermodynamic properties of magnetic alloys, like Cr1-x,.AlxN, in their high-temperature paramagnetic state. Our results unambiguously demonstrate importance of finite temperature effects in theoretical calculations ofthermodynamic properties ofmaterials.

  • 5.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Alling, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Asker, Christian
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ruban, A.V.
    Department of Material Science and Engineering Royal Institute of Technology.
    Phase Stabilities of Alloys From First-Principles2008Inngår i: XVII International Materials Research Congress,2008, Mexico: Mexico , 2008Konferansepaper (Fagfellevurdert)
  • 6.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ponomareva, Alena V.
    Theoretical Physics Department, Moscow Steel and Alloys Institute, Russua.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia.
    Importance of Thermally Induced Magnetic Excitations in First-principles Simulations of Elastic Properties of Transition Metal Alloys2012Inngår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 190, s. 291-294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate the importance of accounting for the complex magnetic ground state and finite temperature magnetic excitations in theoretical simulations of structural and elastic properties of transition metal alloys. Considering Fe72Cr16Ni12 face centered cubic (fcc) alloy, we compare results of first-principles calculations carried out for ferromagnetic and non-magnetic states, as well as for the state with disordered local moments. We show that the latter gives much more accurate description of the elastic properties for paramagnetic alloys. We carry out a determination of the magnetic ground state for fcc Fe-Mn alloys, considering collinear, as well as non-collinear states, and show the sensitively of structural and elastic properties in this system to the detailed alignment between magnetic moments. We therefore conclude that it is essential to develop accurate models of the magnetic state for the predictive description of properties of transition metal alloys.

  • 7.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Fors, Cecilia
    Nobelpriset som fortfarande är en gåta2010Inngår i: Fysikaktuellt, ISSN 0283-9148, nr 2, s. 14-14Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 8.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Kissavos, Andreas E.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Liot, Francois
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Peil, O.
    Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
    Ruban, A. V.
    Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden.
    Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, nr 1, s. 014434-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the results of a systematic ab initio study of the magnetic structure of Fe rich fcc FeNi binary alloys for Ni concentrations up to 50 at. %. Calculations are carried out within density-functional theory using two complementary techniques, one based on the exact muffin-tin orbital theory within the coherent potential approximation and another one based on the projector augmented-wave method. We observe that the evolution of the magnetic structure of the alloy with increasing Ni concentration is determined by a competition between a large number of magnetic states, collinear as well as noncollinear, all close in energy. We emphasize a series of transitions between these magnetic structures, in particular we have investigated a competition between disordered local moment configurations, spin spiral states, the double layer antiferromagnetic state, and the ferromagnetic phase, as well as the ferrimagnetic phase with a single spin flipped with respect to all others. We show that the latter should be particularly important for the understanding of the magnetic structure of the Invar alloys.

  • 9.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Axel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Phase Stability and Elasticity of TiAlN2011Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 4, nr 9, s. 1599-1618Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.

  • 10.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Liot, Francois
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Marten, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Smirnova, E. A.
    Theoretical Physics Department, Moscov Steel and Alloys Institute, Moscow, Russia.
    Magnetism in systems with reduced dimensionality and chemical disorder: the local environment effects2006Inngår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 300, nr 1, s. 211-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study influence of the local chemical environment, the so-called local environment effects, on the electronic structure and properties of magnetic systems with reduced dimensionality and chemical disorder, and show that they play a crucial role in a vicinity of magnetic instability. As a model, we consider Fe–Ni Invar. We present results obtained from ab initio calculations of the electronic structure, magnetic moments, and exchange interactions in random fcc Fe–Ni alloy, for a single monolayer alloy film on a Cu (0 0 1) substrate as well as in the bulk. We analyze the difference between the film and the bulk magnetization, which is found to be most pronounced for dilute alloys. We also analyze a sensitivity of the individual magnetic moments and effective exchange parameters to the local chemical environment of the atoms.

  • 11.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Marten, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Olovsson, Weine
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Local environment effects in random metallic alloys2005Inngår i: The Science of Complex Alloy Phases: proceedings of a symposium held during the TMS Annual Meeting and Exhibition in San Francisco, California, USA, February 13-17, 2005, to honor the Wiliam Hume-Rothery Award recipient Professor Uichiro Mizutani / [ed] Thaddeus B. Massalski and Patrice E. A. Turchi, USA: TMS , 2005, 1, s. 87-108Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This book is published in honor of the 2005 Hume-Rothery Award Recipient, Uichiro Mizutani. It emphasizes both theoretical and experimental aspects of electronic, structural, and thermodynamic properties of complex alloy phases. Leading experts provide an assessment of our current understanding of the structural properties of complex materials, including quasicrystalline and amorphous alloys. Special emphasis is placed on our understanding of why nature is able to stabilize complex atomic arrangements and on recent results related to structurally complex alloy phases. These topics, in the spirit of the work carried out by U. Mizutani, constitute the main theme of the book

  • 12.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Marten, Tobias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Olsson, P.
    Uppsala University.
    Simak, Sergey
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Electronic theory of materials properties: from fundamental understanding towards materials design2006Rapport (Annet vitenskapelig)
    Abstract [en]

           

  • 13.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Mikhaylushkin, Arkady
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Asker, Christian
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Simak, Sergey
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ab initio modeling of alloying effects at extreme conditions2008Inngår i: Second EuroMinScI Conference,2008, France: ESF , 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

       

  • 14.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Nikonov, A. Yu
    Russian Academic Science, Russia .
    Ponomareva, A. V.
    National University of Science and Technology MISiS, Russia .
    Dmitriev, A. I.
    Russian Academic Science, Russia National Research Tomsk State University, Russia .
    Barannikova, S. A.
    Russian Academic Science, Russia National Research Tomsk State University, Russia .
    Theoretical Modeling of Thermodynamic and Mechanical Properties of the Pure Components of Ti and Zr Based Alloys Using the Exact Muffin-Tin Orbitals Method2014Inngår i: Russian Physics Journal, ISSN 1064-8887, E-ISSN 1573-9228, Vol. 56, nr 9, s. 1030-1038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exact muffin-tin orbitals (EMTO) method belongs to the third and latest generation of first-principles methods of calculating the electronic structure of materials in the so-called approximation of muffin-tin (MT) orbitals within the framework of the density functional theory. A study has been performed of its applicability for modeling the thermodynamic and mechanical properties of the pure components of Ti and Zr based alloys. The total energies of Ti, Zr, Nb, V, Mo, and Al are calculated in three crystal structures - face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP). For all of these elements and crystal structures, we have calculated the theoretical values of the lattice constants, elastic constants, and equations of state. The stable crystal structures have been determined. In all cases, calculations by the EMTO method predict the correct structure of the ground state. For stable structures we compared the obtained results with experiment and with calculations using full potential methods. We have demonstrated the reliability of the EMTO method and conclude that its further application for effective modeling of the properties of disordered alloys based on Ti and Zr is possible.

  • 15.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Olovsson, W.
    Uppsala University.
    Wallenius, J.
    Royal Institute of Technology.
    Ab initio simuleringar av materialegenskaper: från grundläggande teori mot design av material2004Inngår i: Nytt från NSC, nr 19, s. 3-5Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 16.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan. NUST MISIS, Russia.
    Ponomareva, A. V.
    NUST MISIS, Russia.
    Nikonov, A. Yu.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Zharmukhambetova, A. M.
    National Research Tomsk State University, Russia.
    Mosyagin, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan. NUST MISIS, Russia.
    Lugovskoy, A. V.
    NUST MISIS, Russia.
    Hellman, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Dmitriev, A. I.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Barannikova, S. A.
    National Research Tomsk State University, Russia; SB RAS, Russia.
    Theoretical description of pressure-induced phase transitions: a case study of Ti-V alloys2015Inngår i: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 35, nr 1, s. 42-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We discuss theoretical description of pressure-induced phase transitions by means of first-principles calculations in the framework of density functional theory. We illustrate applications of theoretical tools that allow one to take into account configurational and vibrational disorders, considering Ti-V alloys as a model system. The universality of the first-principles theory allows us to apply it in studies of different phenomena that occur in the Ti-V system upon compression. Besides the transitions between different crystal structures, we discuss isostructural transitions in bcc Ti-V alloys. Moreover, we present arguments for possible electronic transitions in this system, which may explain peculiar behaviour of elastic properties of V upon compression.

  • 17.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. National University of Science and Technology MISIS, Russia.
    Ponomareva, A. V.
    National University of Science and Technology MISIS, Russia.
    Steneteg, Peter
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Barannikova, S. A.
    National University of Science and Technology MISIS, Russia; National Research Tomsk State University, Russia; SB RAS, Russia.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Recent progress in simulations of the paramagnetic state of magnetic materials2016Inngår i: Current opinion in solid state & materials science, ISSN 1359-0286, E-ISSN 1879-0348, Vol. 20, nr 2, s. 85-106Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    We review recent developments in the field of first-principles simulations of magnetic materials above the magnetic order disorder transition temperature, focusing mainly on 3d-transition metals, their alloys and compounds. We review theoretical tools, which allow for a description of a system with local moments, which survive, but become disordered in the paramagnetic state, focusing on their advantages and limitations. We discuss applications of these theories for calculations of thermodynamic and mechanical properties of paramagnetic materials. The presented examples include, among others, simulations of phase stability of Fe, Fe-Cr and Fe-Mn alloys, formation energies of vacancies, substitutional and interstitial impurities, as well as their interactions in Fe, calculations of equations of state and elastic moduli for 3d-transition metal alloys and compounds, like CrN and steels. The examples underline the need for a proper treatment of magnetic disorder in these systems. (C) 2015 Elsevier Ltd. All rights reserved.

  • 18.
    Adair, R.K.
    et al.
    Department of Physics, Yale University, PO Box 208121, New Haven, CT 06520-8121, United States.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Balzano, Q.
    Dept. of Elec. and Comp. Engineering, A.V. Williams Building, University of Maryland, College Park, MD 20742, United States.
    Comment on "Possible induced enhancement of dispersion forces by cellular phones" by B. E. Sernelius, Phys. Chem. Chem. Phys., 2004, 6, 13632004Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 6, nr 14, s. 3915-3918s. 1363-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    [No abstract available]

  • 19.
    Adamovic, Dragan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Molecular Dynamics Studies of Low-Energy Atom Impact Phenomena on Metal Surfaces during Crystal Growth2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    It is a well-known fact in the materials science community that the use of low-energy atom impacts during thin film deposition is an effective tool for altering the growth behavior and for increasing the crystallinity of the films. However, the manner in which the incident atoms affect the growth kinetics and surface morphology is quite complicated and still not fully understood. This provides a strong incentive for further investigations of the interaction among incident atoms and surface atoms on the atomic scale. These impact-induced energetic events are non-equilibrium, transient processes which complete in picoseconds. The only accessible technique today which permits direct observation of these events is molecular dynamics (MD) simulations.

    This thesis deals with MD simulations of low-energy atom impact phenomena on metal surfaces during crystal growth. Platinum is chosen as a model system given that it has seen extended use as a model surface over the past few decades, both in experiments and simulations. In MD, the classical equations of motion are solved numerically for a set of interacting atoms. The atomic interactions are calculated using the embedded atom method (EAM). The EAM is a semi-empirical, pair-functional interatomic potential based on density functional theory. This potential provides a physical picture that includes many-atom effects while retaining computational efficiency needed for larger systems.

    Single adatoms residing on a surface constitute the smallest possible clusters and are the fundamental components controlling nucleation kinetics. Small two-dimensional clusters on a surface are the result of nucleation and are present during the early stages of growth. These surface structures are chosen as targets in the simulations (papers I and II) to provide further knowledge of the atomistic processes which occur during deposition, to investigate at which impact energies the different kinetic pathways open up, and how they may affect growth behavior. Some of the events observed are adatom scattering, dimer formation, cluster disruption, formation of three-dimensional clusters, and residual vacancy formation. Given the knowledge obtained, papers III and IV deal with growth of several layers with the aim to study the underlying mechanisms responsible for altering growth behavior and how the overall intra- and interlayer atomic migration can be controlled by low-energy atom impacts.

    Delarbeid
    1. Low-energy ion irradiation during film growth: Kinetic pathways leading to enhanced adatom migration rates
    Åpne denne publikasjonen i ny fane eller vindu >>Low-energy ion irradiation during film growth: Kinetic pathways leading to enhanced adatom migration rates
    Vise andre…
    2005 (engelsk)Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, s. 211915-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Embedded-atom molecular dynamics simulations are used to investigate the effects of low-energy self-ion irradiation of Pt adatoms on Pt(111). Here, we concentrate on self-bombardment dynamics, i.e., isolating and monitoring the atomic processes, induced by normally incident Pt atoms with energies E ranging from 5 to 50 eV, that can affect intra- and interlayer mass transport.. We find that adatom scattering, surface channeling, and dimer formation occur at all energies. Atomic intermixing events involving incident and terrace atoms are observed at energies 15  eV, while the collateral formation of residual surface vacancies is observed only with E>40  eV. The overall effect of low-energy self-ion irradiation is to enhance lateral adatom and terrace atom migration. ©2005 American Institute of Physics

    Emneord
    platinum, adsorbed layers, ion beam effects, molecular dynamics method, channelling, vacancies (crystal), diffusion, metallic thin films, surface structure
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13934 (URN)10.1063/1.1940122 (DOI)
    Tilgjengelig fra: 2006-08-29 Laget: 2006-08-29 Sist oppdatert: 2017-12-13
    2. Enhanced intra- and interlayer mass transport on Pt(111) via 5 - 50 eV Pt atom impacts on two-dimensional Pt clusters
    Åpne denne publikasjonen i ny fane eller vindu >>Enhanced intra- and interlayer mass transport on Pt(111) via 5 - 50 eV Pt atom impacts on two-dimensional Pt clusters
    Vise andre…
    2006 (engelsk)Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 4, s. 2235-2243Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Embedded-atom molecular dynamics simulations were used to investigate the effects of low-energy (5–50 eV) normally-incident self-ion irradiation of two-dimensional compact Pt3, Pt7, Pt19, and Pt37 clusters on Pt(111). We follow atomistic pathways leading to bombardment-induced intra- and interlayer mass transport. The results can be described in terms of three impact energy regimes. With E ≤ 20 eV, we observe an increase in 2D island dimensions and negligible residual point defect formation. As the impact energy is raised above 20 eV, we observe an increase in irradiation-induced lateral mass transport, a decrease in island size, and the activation of interlayer processes. For E ≥ 35 eV, this trend continues, but point defects, in the form of surface vacancies, are also formed. The results illustrate the richness of the dynamical interaction mechanisms occurring among incident energetic species, target clusters, and substrate atoms, leading to island preservation, reconfiguration, disruption and/or residual point defects formation. We discuss the significance of these results in terms of thin film growth.

    Emneord
    Ion bombardment; Platinum; Clusters; Atomistic dynamics
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13935 (URN)10.1016/j.tsf.2006.05.028 (DOI)
    Tilgjengelig fra: 2006-08-29 Laget: 2006-08-29 Sist oppdatert: 2017-12-13
    3. Kinetic pathways leading to layer-by-layer growth from hyperthermal atoms: A Multibillion time step molecular dynamics study
    Åpne denne publikasjonen i ny fane eller vindu >>Kinetic pathways leading to layer-by-layer growth from hyperthermal atoms: A Multibillion time step molecular dynamics study
    Vise andre…
    2007 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, s. 115418-115425Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We employ multibillion time step embedded-atom molecular dynamics simulations to investigate the homoepitaxial growth of Pt(111) from hyperthermal Pt atoms (EPt=0.2–50eV) using deposition fluxes approaching experimental conditions. Calculated antiphase diffraction intensity oscillations, based on adatom coverages as a function of time, reveal a transition from a three-dimensional multilayer growth mode with EPt<20eV to a layer-by-layer growth with EPt≥20eV. We isolate the effects of irradiation-induced processes and thermally activated mass transport during deposition in order to identify the mechanisms responsible for promoting layer-by-layer growth. Direct evidence is provided to show that the observed transition in growth modes is primarily due to irradiation-induced processes which occur during the 10ps following the arrival of each hyperthermal atom. The kinetic pathways leading to the transition involve both enhanced intralayer and interlayer adatom transport, direct incorporation of energetic atoms into clusters, and cluster disruption leading to increased terrace supersaturation.

    sted, utgiver, år, opplag, sider
    American Physical Society, 2007
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-38795 (URN)10.1103/PhysRevB.76.115418 (DOI)45667 (Lokal ID)45667 (Arkivnummer)45667 (OAI)
    Merknad

    The previous status of this article was Manuscript.

    Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2017-12-13bibliografisk kontrollert
    4. Controlled intra- and interlayer mass transport during low-energy Pt(111) homoepitaxy
    Åpne denne publikasjonen i ny fane eller vindu >>Controlled intra- and interlayer mass transport during low-energy Pt(111) homoepitaxy
    Vise andre…
    (engelsk)Manuskript (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13937 (URN)
    Tilgjengelig fra: 2006-08-29 Laget: 2006-08-29 Sist oppdatert: 2014-04-14
  • 20.
    Adamovic, Dragan
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Chirita, Valeriu
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Münger, Peter
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Greene, J.E.
    Materials Science Department and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, USA.
    Kinetic pathways leading to layer-by-layer growth from hyperthermal atoms: A Multibillion time step molecular dynamics study2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, s. 115418-115425Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We employ multibillion time step embedded-atom molecular dynamics simulations to investigate the homoepitaxial growth of Pt(111) from hyperthermal Pt atoms (EPt=0.2–50eV) using deposition fluxes approaching experimental conditions. Calculated antiphase diffraction intensity oscillations, based on adatom coverages as a function of time, reveal a transition from a three-dimensional multilayer growth mode with EPt<20eV to a layer-by-layer growth with EPt≥20eV. We isolate the effects of irradiation-induced processes and thermally activated mass transport during deposition in order to identify the mechanisms responsible for promoting layer-by-layer growth. Direct evidence is provided to show that the observed transition in growth modes is primarily due to irradiation-induced processes which occur during the 10ps following the arrival of each hyperthermal atom. The kinetic pathways leading to the transition involve both enhanced intralayer and interlayer adatom transport, direct incorporation of energetic atoms into clusters, and cluster disruption leading to increased terrace supersaturation.

  • 21.
    Adamovic, Dragan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Chirita, Valeriu
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Greene, Joe
    Controlled intra- and interlayer mass transport during low-energy Pt(111) homoepitaxyManuskript (Annet vitenskapelig)
  • 22.
    Adamovic, Dragan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greene, Joe
    University of Illinois.
    Enhanced intra- and interlayer mass transport on Pt(111) via 5 - 50 eV Pt atom impacts on two-dimensional Pt clusters2006Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, nr 4, s. 2235-2243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Embedded-atom molecular dynamics simulations were used to investigate the effects of low-energy (5–50 eV) normally-incident self-ion irradiation of two-dimensional compact Pt3, Pt7, Pt19, and Pt37 clusters on Pt(111). We follow atomistic pathways leading to bombardment-induced intra- and interlayer mass transport. The results can be described in terms of three impact energy regimes. With E ≤ 20 eV, we observe an increase in 2D island dimensions and negligible residual point defect formation. As the impact energy is raised above 20 eV, we observe an increase in irradiation-induced lateral mass transport, a decrease in island size, and the activation of interlayer processes. For E ≥ 35 eV, this trend continues, but point defects, in the form of surface vacancies, are also formed. The results illustrate the richness of the dynamical interaction mechanisms occurring among incident energetic species, target clusters, and substrate atoms, leading to island preservation, reconfiguration, disruption and/or residual point defects formation. We discuss the significance of these results in terms of thin film growth.

  • 23.
    Adamovic, Dragan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greene, Joe
    University of Illinois.
    Low-energy ion irradiation during film growth: Kinetic pathways leading to enhanced adatom migration rates2005Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, s. 211915-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Embedded-atom molecular dynamics simulations are used to investigate the effects of low-energy self-ion irradiation of Pt adatoms on Pt(111). Here, we concentrate on self-bombardment dynamics, i.e., isolating and monitoring the atomic processes, induced by normally incident Pt atoms with energies E ranging from 5 to 50 eV, that can affect intra- and interlayer mass transport.. We find that adatom scattering, surface channeling, and dimer formation occur at all energies. Atomic intermixing events involving incident and terrace atoms are observed at energies 15  eV, while the collateral formation of residual surface vacancies is observed only with E>40  eV. The overall effect of low-energy self-ion irradiation is to enhance lateral adatom and terrace atom migration. ©2005 American Institute of Physics

  • 24.
    Aichhorn, Markus
    et al.
    Graz University of Technology.
    Pourovskii, Leonid
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Georges, Antoine
    Ecole Polytech.
    Importance of electronic correlations for structural and magnetic properties of the iron pnictide superconductor LaFeAsO2011Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 5, s. 054529-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present calculations of structural and magnetic properties of the iron-pnictide superconductor LaFeAsO including electron-electron correlations. For this purpose we apply a fully charge self-consistent combination of density-functional theory with the dynamical mean-field theory, allowing for the calculation of total energies. We find that the inclusion of correlation effects gives a good agreement of the arsenic z position with experimental data even in the paramagnetic (high-temperature) phase. Going to low temperatures, we study the formation of the ordered moment in the striped spin-density-wave phase, yielding an ordered moment of about 0.60 mu(B), again in good agreement with experiments. This shows that the inclusion of correlation effects improves both structural and magnetic properties of LaFeAsO at the same time.

  • 25.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Configurational and Magnetic Interactions in Multicomponent Systems2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is a theoretical study of configurational and magnetic interactions in multicomponent solids. These interactions are the projections onto the configurational and magnetic degrees of freedom of the underlying electronic quantum mechanical system, and can be used to model, explain and predict the properties of materials. For example, the interactions govern temperature induced configurational and magnetic order-disorder transitions in Heusler alloys and ternary nitrides.

    In particular three perspectives are studied. The first is how the interactions can be derived from first-principles calculations at relevant physical conditions. The second is their consequences, like the critical temperatures for disordering, obtained with e.g. Monte Carlo simulations. The third is their origin in terms of the underlying electronic structure of the materials.

    Intrinsic defects in the half-Heusler system NiMnSb are studied and it is found that low-energy defects do not destroy the important half-metallic property at low concentrations. Deliberate doping of NiMnSb with 3d-metals is considered and it is found that replacing some Ni with extra Mn or Cr creates new strong magnetic interactions which could be beneficial for applications at elevated temperature. A self-consistent scheme to include the effects of thermal expansion and one-electron excitations in the calculation of the magnetic critical temperature is introduced and applied to a study of Ni1−xCuxMnSb.

    A supercell implementation of the disordered local moments approach is suggested and benchmarked for the treatment of paramagnetic CrN as a disordered magnetic phase. It is found that the orthorhombic-to-cubic phase transition in this nitride can be understood as a first-order magnetic order-disorder transition. The ferromagnetism in Ti1−xCrxN solid solutions, an unusual property in nitrides, is explained in terms of a charge transfer induced change in the Cr-Cr magnetic interactions.

    Cubic Ti1−xAlxN solid solutions displays a complex and concentration dependent phase separation tendency. A unified cluster expansion method is presented that can be used to simulate the configurational thermodynamics of this system. It is shown that short range clustering do influence the free energy of mixing but only slightly change the isostructural phase diagram as compared to mean-field estimates.

    Delarbeid
    1. Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb
    Åpne denne publikasjonen i ny fane eller vindu >>Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb
    2006 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, nr 6, s. 064418-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The first material to be predicted from first-principles calculations as half-metallic was NiMnSb, and the research on this material has been intense due to its possible applications in spintronics devices. The failure of many experiments to measure spin polarization to more than a fraction of the predicted 100% has partly been blamed on structural defects. In this work a complete first-principles treatise of point defects, including nonstoichiometric antisites, interstitial and vacancy defects, as well as stoichiometric atomic swap defects in NiMnSb, is presented. We find that the formation energies of the defects span a large scale from 0.2 to 14.4 eV. The defects with low formation energies preserve the half-metallic character of the material. We also find that some of the defects increase the magnetic moment and thus can explain the experimentally observed increase of magnetic moments in some samples of NiMnSb. Most interesting in this respect are Mn interstitials which increase the magnetic moment, have a low formation energy, and keep the half-metallic character of the material.

    Emneord
    nickel alloys, manganese alloys, antimony alloys, ferromagnetic materials, ab initio calculations, interstitials, antisite defects, vacancies (crystal), defect states, magnetic moments
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-35025 (URN)10.1103/PhysRevB.73.064418 (DOI)24646 (Lokal ID)24646 (Arkivnummer)24646 (OAI)
    Merknad
    Original Publication: Björn Alling, Sam Shallcross and Igor Abrikosov, Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb, 2006, Physical Review B. Condensed Matter and Materials Physics, (73), 6, 064418. http://dx.doi.org/10.1103/PhysRevB.73.064418 Copyright: American Physical Society http://www.aps.org/ Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2017-12-13
    2.
    Posten ble ikke funnet. Det kan skyldes at posten ikke lenger er tilgjengelig eller det er feil id i adressefeltet.
    3.
    Posten ble ikke funnet. Det kan skyldes at posten ikke lenger er tilgjengelig eller det er feil id i adressefeltet.
    4. Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys
    Åpne denne publikasjonen i ny fane eller vindu >>Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys
    Vise andre…
    2007 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, nr 1, s. 014434-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We report on the results of a systematic ab initio study of the magnetic structure of Fe rich fcc FeNi binary alloys for Ni concentrations up to 50 at. %. Calculations are carried out within density-functional theory using two complementary techniques, one based on the exact muffin-tin orbital theory within the coherent potential approximation and another one based on the projector augmented-wave method. We observe that the evolution of the magnetic structure of the alloy with increasing Ni concentration is determined by a competition between a large number of magnetic states, collinear as well as noncollinear, all close in energy. We emphasize a series of transitions between these magnetic structures, in particular we have investigated a competition between disordered local moment configurations, spin spiral states, the double layer antiferromagnetic state, and the ferromagnetic phase, as well as the ferrimagnetic phase with a single spin flipped with respect to all others. We show that the latter should be particularly important for the understanding of the magnetic structure of the Invar alloys.

    sted, utgiver, år, opplag, sider
    American Physical Society, 2007
    Emneord
    Iron alloys, nickel alloys, ferromagnetic materials, magnetic structure, ab initio calculations, density functional theory, linear muffin-tin orbital method, local moments
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-14277 (URN)10.1103/PhysRevB.76.014434 (DOI)
    Merknad
    Original Publication: Igor A. Abrikosov, Andreas E. Kissavos, Francois Liot, Björn Alling, Sergey Simak, O. Peil and A. V. Ruban, Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys, 2007, Physical Review B Condensed Matter, (76), 1, 014434. http://dx.doi.org/10.1103/PhysRevB.76.014434 Copyright: American Physical Society http://www.aps.org/Tilgjengelig fra: 2007-02-01 Laget: 2007-02-01 Sist oppdatert: 2017-12-13bibliografisk kontrollert
    5. Questionable collapse of the bulk modulus in CrN
    Åpne denne publikasjonen i ny fane eller vindu >>Questionable collapse of the bulk modulus in CrN
    2010 (engelsk)Inngår i: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 9, nr 4, s. 283-284Artikkel i tidsskrift, Letter (Annet vitenskapelig) Published
    Abstract [en]

    In this comment we show that the main conclusion in a previous article, claiminga drastic increase in compressibility of CrN at the cubic to orthorhombic phasetransition, is unsupported by first-principles calculations. We show that if thecubic CrN phase is considered as a disordered magnetic material, as supported bydifferent experimental data, rather then non-magnetic, the bulk modulus is almostunaffected by the transition.

    sted, utgiver, år, opplag, sider
    London, UK: Nature Publishing Group, 2010
    Emneord
    CrN, phase-transition, magnetism, bulk modulus, first-principles
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-60438 (URN)10.1038/nmat2722 (DOI)000275901000002 ()
    Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    6. Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN
    Åpne denne publikasjonen i ny fane eller vindu >>Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN
    2010 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, s. 184430-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Two different methods for the modeling of a magnetically disordered CrN stateusing a supercell approach are investigated. They are found to give equivalentresults of the total energy, being also similar to results obtained with an effectivemedium approach. Furthermore, CrN is shown to be better described using aLDA+U framework for the treatment of electron-electron correlations as comparedto GGA or LDA calculations. Modeling the cubic paramagnetic phase with ourmodels for magnetic disorder and considering the strong electron correlations, thetemperature and pressure induced phase transitions in CrN can be explained.

    sted, utgiver, år, opplag, sider
    American institute of physics, 2010
    Emneord
    CrN, magnetic disorder, nitrides, LDA+U, SQS, phase transition, chromium compounds
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-60439 (URN)10.1103/PhysRevB.82.184430 (DOI)000291462500005 ()
    Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12
    7. Theory of the ferromagnetism in Ti1-xCrxN solid solutions
    Åpne denne publikasjonen i ny fane eller vindu >>Theory of the ferromagnetism in Ti1-xCrxN solid solutions
    2010 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, nr 5, s. 054408-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    First-principles calculations are used to investigate the magnetic properties of Ti1‑xCrxN solid solutions. We show that the magnetic interactions between Cr spins that favor antiferromagnetism in CrN is changed upon alloying with TiN leading to the appearance of ferromagnetism in the system at approximately x≤0.50 in agreement with experimental reports. Furthermore we suggest that this effect originates in an electron density redistribution from Ti to Cr that decreases the polarization of Crd states with t2g symmetry while it increases the polarization of Crd states with eg symmetry, both changes working in favor of ferromagnetism.

    Emneord
    TiN, CrN, TiCrN, solid solutions, first-principles, magnetic interactions, ferromagnetism, electronic structure
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-60441 (URN)10.1103/PhysRevB.82.054408 (DOI)
    Merknad
    Original Publication: Björn Alling, Theory of the ferromagnetism in Ti1-xCrxN solid solutions, 2010, Physical Review B Condensed Matter, (82), 5, 054408. http://dx.doi.org/10.1103/PhysRevB.82.054408 Copyright: American Physical Society http://www.aps.org/Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12
    8. A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN
    Åpne denne publikasjonen i ny fane eller vindu >>A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN
    Vise andre…
    2011 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, nr 10, s. 104203-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We use a study of the cubic Ti1−xAlxN system to illustrate a practical way of combining the major methodologies within alloy theory, the Connolly-Williams cluster expansion and the generalized perturbation method, in order to solve difficult alloy problems. The configurational, concentration dependent, Hamiltonian is separated into a fixed-lattice and a local lattice relaxation part. The effective cluster interactions of the first part is obtained primarily with a GPM-based approach while the later is obtained using cluster expansion. In our case the impact on the isostructural phase diagram of considering short range clustering beyond the mean field approximation, obtained from the mixing enthalpy and entropy of the random alloy, is rather small, especially in the composition region x ≤ 0.66, within reach of thin film growth techniques.

    sted, utgiver, år, opplag, sider
    American Physical Society, 2011
    Emneord
    TiAlN, TiN, AlN, cluster expansion, GPM, spinodal decomposition, first-principles, titanium aluminium nitride, clustering, phase separation
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-60442 (URN)10.1103/PhysRevB.83.104203 (DOI)000288782700004 ()
    Merknad
    Original Publication: Björn Alling, A. V. Ruban, A Karimi, Lars Hultman and Igor Abrikosov, A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN, 2011, Physical Review B. Condensed Matter and Materials Physics, (83), 10, 104203. http://dx.doi.org/10.1103/PhysRevB.83.104203 Copyright: American Physical Society http://www.aps.org/ Tilgjengelig fra: 2010-10-13 Laget: 2010-10-13 Sist oppdatert: 2017-12-12
    9. Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN
    Åpne denne publikasjonen i ny fane eller vindu >>Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN
    2009 (engelsk)Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, nr 181906Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The influence of pressure on the phase stabilities of Ti1−xAlxN solid solutions has been studied using first principles calculations. We find that the application of hydrostatic pressure enhances the tendency for isostructural decomposition, including spinodal decomposition. The effect originates in the gradual pressure stabilization of cubic AlN with respect to the wurtzite structure and an increased isostructural cubic mixing enthalpy with increased pressure. The influence is sufficiently strong in the composition-temperature interval corresponding to a shoulder of the spinodal line that it could impact the stability of the material at pressures achievable in the tool-work piece contact during cutting operations

    Emneord
    ab initio calculations, aluminium compounds, enthalpy, high-pressure effects, mixing, solid solutions, spinodal decomposition, titanium compounds
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-51569 (URN)10.1063/1.3256196 (DOI)
    Merknad
    Original Publication: Björn Alling, Magnus Odén, Lars Hultman and Igor Abrikosov, Pressure enhancement of the isostructural cubic decomposition in Ti1-xAlxN, 2009, Applied Physics Letters, (95), 181906. http://dx.doi.org/10.1063/1.3256196 Copyright: American Institute of Physics http://www.aip.org/ Tilgjengelig fra: 2009-11-07 Laget: 2009-11-07 Sist oppdatert: 2017-12-12
    10. Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions
    Åpne denne publikasjonen i ny fane eller vindu >>Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions
    Vise andre…
    2010 (engelsk)Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, nr 22, s. 224101-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Thin solid films of metastable rocksalt structure (c-) Sc1-xAlxN and Ti1-xAlxN were employed as model systems to investigate the relative influence of volume mismatch and electronic structure driving forces for phase separation. Reactive dual magnetron sputtering was used to deposit stoichiometric Sc0.57Al0.43N(111) and Ti0.51Al0.49N(111) thin films, at 675 °C and 600 °C, respectively, followed by stepwise annealing to a maximum temperature of 1100 °C. Phase transformations during growth and annealing were followed in situ using X-ray scattering. The results show that the as-deposited Sc0.57Al0.43N films phase separate at 1000 °C – 1100 °C into non-isostructural c-ScN and wurtzite-structure (w-) AlN, via nucleation and growth at domain boundaries. Ti0.51Al0.49N, however, exhibits spinodal decomposition into isostructural coherent c-TiN and c-AlN, in the temperature interval of 800 °C – 1000 °C. X-ray pole figures show the coherency between c-ScN and w-AlN, with AlN(0001) || ScN(001) and AlN<01ɸ10> || ScN<1ɸ10>. First principles calculations of mixing energy-lattice spacing curves explain the results on a fundamental physics level and open a route for design of novel metastable pseudobinary phases for hard coatings and electronic materials.

    Emneord
    TiAlN, ScAlN, spinodal decomposition, nitrides, TiN, ScN, AlN, XRD, TEM, first-principles, phase separation, meta stable
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-56270 (URN)10.1103/PhysRevB.81.224101 (DOI)000278300900004 ()
    Merknad
    Original Publication: Carina Höglund, Björn Alling, Jens Birch, Manfred Beckers, Per O. Å. Persson, Carsten Baehtz, Zsolt Czigány, Jens Jensen and Lars Hultman, Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions, 2010, Physical Review B. Condensed Matter and Materials Physics, (81), 22, 224101. http://dx.doi.org/10.1103/PhysRevB.81.224101 Copyright: American Physical Society http://www.aps.org/ Tilgjengelig fra: 2010-05-06 Laget: 2010-05-06 Sist oppdatert: 2017-12-12
    11.
    Posten ble ikke funnet. Det kan skyldes at posten ikke lenger er tilgjengelig eller det er feil id i adressefeltet.
  • 26.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hårda ytors egenskaper avslöjas med beräkningar2010Inngår i: Fysikaktuellt, nr 3, s. 6-8Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    n/a

  • 27.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Theory of the ferromagnetism in Ti1-xCrxN solid solutions2010Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, nr 5, s. 054408-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First-principles calculations are used to investigate the magnetic properties of Ti1‑xCrxN solid solutions. We show that the magnetic interactions between Cr spins that favor antiferromagnetism in CrN is changed upon alloying with TiN leading to the appearance of ferromagnetism in the system at approximately x≤0.50 in agreement with experimental reports. Furthermore we suggest that this effect originates in an electron density redistribution from Ti to Cr that decreases the polarization of Crd states with t2g symmetry while it increases the polarization of Crd states with eg symmetry, both changes working in favor of ferromagnetism.

  • 28.
    Alling, Björn
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ekholm, Marcus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Doping the half-Heusler alloy NiMnSb with magnetic 3d-metals2008Inngår i: Workshop New Challenges in the Electronic Structure of Complex Materials,2008, Hungary: Hungary , 2008Konferansepaper (Fagfellevurdert)
  • 29.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Energetics and magnetic impact of 3d-metal doping of the half-metallic ferromagnet NiMnSb2008Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 77, nr 14, s. 144414-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have performed a theoretical study of the effect of doping the half-Heusler alloy NiMnSb with the magnetic 3d metals Cr, Mn, Fe, Co, and Ni, with respect to both energetics and magnetic properties. Starting from the formation energies, we discuss the possibility of placing the dopant on different crystallographic positions in the alloy. We calculate total and local magnetic moments, effective exchange interactions, and density of states and also outline strategies to tune the magnetic properties of the alloy. Doping of NiMnSb with Cr as well as substituting some Ni with extra Mn have the largest impact on magnetic interactions in the system while preserving its half-metallic property. Therefore, we suggest the possibility that these dopants increase the thermal stability of half-metallicity in NiMnSb, with implications for its possible usage in spintronics applications.

  • 30.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultberg, L
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Strong electron correlations stabilize paramagnetic cubic Cr1-xAlxN solid solutions2013Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stability of rock salt structure cubic Cr1-xAlxN solid solutions at high Al content and high temperature has made it one of the most important materials systems for protective coating applications. We show that the strong electron correlations in a material with dynamic magnetic disorder is the underlying reason for the observed stability against isostructural decomposition. This is done by using the first-principles disordered local moments molecular dynamics technique, which allows us to simultaneously consider electronic, magnetic, and vibrational degrees of freedom.

  • 31.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary (M1-xMxB2)-M-1-B-2 alloys with AlB2 type structure2015Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary (M1-xMxB2)-M-1-B-2 alloys comprising (MB2)-B-i (M-i = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1-xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at E-F in TiB2, ZrB2, and HfB2.

  • 32.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hall-Wilton, R.
    European Spallat Source ESS AB.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mixing thermodynamics of TM(1-x)Gd(x)N (TM=Ti, Zr, Hf) from first principles2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 24, s. 241911-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mixing thermodynamics of GdN with TiN, ZrN, and HfN is studied using first-principles methods. We find that while Ti(1-x)Gd(x)N has a strong preference for phase separation due to the large lattice mismatch, Zr(1-x)Gd(x)N and Hf(1-x)Gd(x)N readily mix, possibly in the form of ordered compounds. In particular, ZrGdN(2) is predicted to order in a rocksalt counterpart to the L1(1) structure at temperatures below 1020 K. These mixed nitrides are promising candidates as neutron absorbing, thermally and chemically stable, thin film materials.

  • 33.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Isaev, Eyvas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Flink, Axel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Metastability of fcc-related Si-N phases2008Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, nr 13, s. 132103-132103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The phenomenon of superhardening in TiN/SiNx nanocomposites and the prediction of extreme hardness in bulk gamma-Si3N4 have attracted a large interest to this material system. Attempts to explain the experimental findings by means of first-principles calculations have so far been limited to static calculations. The dynamical stability of suggested structures of the SiNx tissue phase critical for the understanding of the nanocomposites is thus unknown. Here, we present a theoretical study of the phonon-dispersion relations of B1 and B3 SiN. We show that both phases previously considered as metastable are dynamically unstable. Instead, two pseudo-B3 Si3N4 phases derived from a L1(2)- or D0(22)-type distribution of Si vacancies are dynamically stable and might explain recent experimental findings of epitaxial SiNx in TiN/SiNx multilayers.

  • 34.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Karimi, A
    Swiss Federal Institute of Technology.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Electronic origin of the isostructural decomposition in cubic M1-xAlxN (M=Ti, Cr, Sc, Hf): A first-principles study2008Inngår i: Surface and Coatings Technology, ISSN 0257-8972, Vol. 203, nr 5-7, s. 883-886Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have used first-principles calculations to investigate the mixing enthalpies, lattice parameters and electronic density of states of the ternary nitride systems Ti1-xAlxN, Cr1-xAlxN, Sc1-xAlxN and Hf1-xAlxN in the cubic B1 structure where the transition metals and aluminium form a solid solution on the metal sublattice. We discuss the electronic origins of the possible isostructural decomposition in these materials relevant for hard coatings applications. We find that in the systems Ti1-xAlxN and Hf1-xAlxN the electronic structure effects strongly influences the phase stability as d-states are localised at the Fermi level in AlN-rich samples. This leads to a strongly asymmetric contribution to the mixing enthalpy, an effect not present in Cr1-xAlxN and Sc1-xAlxN. The lattice mismatch is large in Sc1-xAlxN and Hf1-xAlxN, giving a symmetric contribution to the mixing enthalpies in those systems.

  • 35.
    Alling, Björn
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Karimi, A.
    Institute of Physics of Complex Matter.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    First-principles study of the effect of nitrogen vacancies on the decomposition pattern in cubic Ti1-xAlxN1-y2008Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, s. 071903-1-071903-3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

      The effect of nitrogen substoichiometry on the isostructural phase stabilities of the cubic Ti1−xAlxN1−y system has been investigated using first-principles calculations. The preferred isostructural decomposition pattern in these metastable solid solutions was predicted from the total energy calculations on a dense concentration grid. Close to the stoichiometric Ti1−xAlxN1 limit, N vacancies increase the tendency for phase separation as N sticks to Al while the vacancies prefers Ti neighbors. For nitrogen depleated conditions, N sticks to Ti forming TiN (0<<1) while Al tends to form nitrogen-free fcc-Al or Al–Ti alloys.

  • 36.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Khatibi, Ali
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutionsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    First-principles calculations are employed to investigate the stability and properties of cubic rock-salt like (Cr1−xAlx)2O3 solid solutions, stabilized by metal site vacancies as recently reported experimentally. It is demonstrated that the metal site vacancies can indeed be ordered in a way that gives rise to a favorable coordination of all O atoms in the lattice. B1-like structures with ordered and disordered metal site vacancies are studied for (Cr0.5Al0.5)2O3 and found to a have cubic lattice spacing close to the values reported experimentally, in contrast to fluorite-like and perovskite structures. The obtained B1-like structures are higher in energy than corundum solid solutions for all compositions, but with an energy offset per atom similar to other metastable systems possible to synthesize with physical vapor deposition techniques. The obtained electronic structures show that the B1-like systems are semiconducting although with smaller band gaps than the corundum structure.

  • 37.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Khatibi, Ali
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Theoretical investigation of cubic B1-like and corundum (Cr1−xAlx)2O3 solid solutions2013Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 31, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    First-principles calculations are employed to investigate the stability and properties of cubic rock-salt-like (Cr1−xAlx)2O3 solid solutions, stabilized by metal site vacancies as recently reported experimentally. It is demonstrated that the metal site vacancies can indeed be ordered in a way that gives rise to a suitable fourfold coordination of all O atoms in the lattice. B1-like structures with ordered and disordered metal site vacancies are studied for (Cr0.5Al0.5)2O3 and found to have a cubic lattice spacing close to the values reported experimentally, in contrast to fluorite-like and perovskite structures. The obtained B1-like structures are higher in energy than corundum solid solutions for all compositions, but with an energy offset per atom similar to other metastable systems possible to synthesize with physical vapor deposition techniques. The obtained electronic structures show that the B1-like systems are semiconducting although with smaller band gaps than the corundum structure.

  • 38.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Max Planck Institute Eisenforsch GmbH, Germany.
    Koermann, F.
    Max Planck Institute Eisenforsch GmbH, Germany; Delft University of Technology, Netherlands.
    Grabowski, B.
    Max Planck Institute Eisenforsch GmbH, Germany.
    Glensk, A.
    Max Planck Institute Eisenforsch GmbH, Germany.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. National University of Science and Technology MISIS, Russia.
    Neugebauer, J.
    Max Planck Institute Eisenforsch GmbH, Germany.
    Strong impact of lattice vibrations on electronic and magnetic properties of paramagnetic Fe revealed by disordered local moments molecular dynamics2016Inngår i: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, nr 22, artikkel-id 224411Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the impact of lattice vibrations on magnetic and electronic properties of paramagnetic bcc and fcc iron at finite temperature, employing the disordered local moments molecular dynamics (DLM-MD) method. Vibrations strongly affect the distribution of local magnetic moments at finite temperature, which in turn correlates with the local atomic volumes. Without the explicit consideration of atomic vibrations, the mean local magnetic moment and mean field derived magnetic entropy of paramagnetic bcc Fe are larger compared to paramagnetic fcc Fe, which would indicate that the magnetic contribution stabilizes the bcc phase at high temperatures. In the present study we show that this assumption is not valid when the coupling between vibrations and magnetism is taken into account. At the gamma-delta transition temperature (1662 K), the lattice distortions cause very similar magnetic moments of both bcc and fcc structures and hence magnetic entropy contributions. This finding can be traced back to the electronic densities of states, which also become increasingly similar between bcc and fcc Fe with increasing temperature. Given the sensitive interplay of the different physical excitation mechanisms, our results illustrate the need for an explicit consideration of vibrational disorder and its impact on electronic and magnetic properties to understand paramagnetic Fe. Furthermore, they suggest that at the gamma-delta transition temperature electronic and magnetic contributions to the Gibbs free energy are extremely similar in bcc and fcc Fe.

  • 39.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Marten, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN2010Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, s. 184430-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two different methods for the modeling of a magnetically disordered CrN stateusing a supercell approach are investigated. They are found to give equivalentresults of the total energy, being also similar to results obtained with an effectivemedium approach. Furthermore, CrN is shown to be better described using aLDA+U framework for the treatment of electron-electron correlations as comparedto GGA or LDA calculations. Modeling the cubic paramagnetic phase with ourmodels for magnetic disorder and considering the strong electron correlations, thetemperature and pressure induced phase transitions in CrN can be explained.

  • 40.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Marten, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Questionable collapse of the bulk modulus in CrN2010Inngår i: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 9, nr 4, s. 283-284Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    In this comment we show that the main conclusion in a previous article, claiminga drastic increase in compressibility of CrN at the cubic to orthorhombic phasetransition, is unsupported by first-principles calculations. We show that if thecubic CrN phase is considered as a disordered magnetic material, as supported bydifferent experimental data, rather then non-magnetic, the bulk modulus is almostunaffected by the transition.

  • 41.
    Alling, Björn
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Marten, Tobias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Karimi, A.
    Swiss Federal Institute of Technology Lausanne, Switzerland.
    Comparison of thermodynamic properties of cubic Cr 1-x Al x N and Ti 1-x Al x N from first-principles calculations2007Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, nr 044314Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to investigate the stability of the cubic phase of Cr1−xAlxN at high AlN content, first principles calculations of magnetic properties, lattice parameters, electronic structure, and mixing enthalpies of the system were performed. The mixing enthalpy was calculated on a fine concentration mesh to make possible the accurate determination of its second concentration derivative. The results are compared to calculations performed for the related compound Ti1−xAlxN and with experiments. The mixing enthalpy is discussed in the context of isostructural spinodal decomposition. It is shown that the magnetism is the key to understand the difference between the Cr- and Ti-containing systems. Cr1−xAlxN turns out to be more stable against spinodal decomposition than Ti1−xAlxN, especially for AlN-rich samples which are of interest in cutting tools applications.

  • 42.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN2009Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, nr 181906Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of pressure on the phase stabilities of Ti1−xAlxN solid solutions has been studied using first principles calculations. We find that the application of hydrostatic pressure enhances the tendency for isostructural decomposition, including spinodal decomposition. The effect originates in the gradual pressure stabilization of cubic AlN with respect to the wurtzite structure and an increased isostructural cubic mixing enthalpy with increased pressure. The influence is sufficiently strong in the composition-temperature interval corresponding to a shoulder of the spinodal line that it could impact the stability of the material at pressures achievable in the tool-work piece contact during cutting operations

  • 43.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ruban, A V
    Royal Institute of Technology.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Effect of thermal expansion, electronic excitations, and disorder on the Curie temperature of Ni1-xCuxMnSb alloys2009Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, nr 13, s. 134417-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate the importance of thermal effects such as temperature-induced electronic, magnetic and vibrational excitations, as well as structural defects in the first-principles calculations of the magnetic critical temperature of complex alloys using half-Heusler Ni1-xCuxMnSb alloys as a case study. The thermal lattice expansion and one-electron excitations have been accounted for self-consistently in the Curie temperature calculations. In the Ni-rich region, electronic excitations, thermal expansion, and structural defects substantially decrease the calculated Curie temperature. At the same time, some defects are shown to increase T-C in Cu-rich samples.

  • 44.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ruban, A. V.
    Royal Institute of Technology, Department of Material Science and Engineering.
    Karimi, A
    Ecole Polytechnique Federale de Lausanne, IPMC.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN2011Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, nr 10, s. 104203-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use a study of the cubic Ti1−xAlxN system to illustrate a practical way of combining the major methodologies within alloy theory, the Connolly-Williams cluster expansion and the generalized perturbation method, in order to solve difficult alloy problems. The configurational, concentration dependent, Hamiltonian is separated into a fixed-lattice and a local lattice relaxation part. The effective cluster interactions of the first part is obtained primarily with a GPM-based approach while the later is obtained using cluster expansion. In our case the impact on the isostructural phase diagram of considering short range clustering beyond the mean field approximation, obtained from the mixing enthalpy and entropy of the random alloy, is rather small, especially in the composition region x ≤ 0.66, within reach of thin film growth techniques.

  • 45.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ruban, A. V.
    Royal Institute of Technology, Stockholm.
    Karimi, A.
    Swiss Federal Institute of Technology Lausanne (EPFL).
    Peil, O. E.
    Uppsala University.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Mixing and decomposition thermodynamics of c-Ti1-xAlxN from first-principles calculations2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, nr 045123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wedescribe an efficient first-principles method that can be used tocalculate mixing enthalpies of transition metal nitrides with B1 structureand substitutional disorder at the metal sublattice. The technique isbased on the density functional theory. The independent sublattice modelis suggested for the treatment of disorder-induced local lattice relaxationeffects. It supplements the description of the substitutional disorder withinthe coherent potential approximation. We demonstrate the excellent accuracy ofthe method by comparison with calculations performed by means ofthe projector augumented wave method on supercells constructed as specialquasirandom structures. At the same time, the efficiency of thetechnique allows for total energy calculations on a very finemesh of concentrations which enables a reliable calculation of thesecond concentration derivative of the alloy total energy. This isa first step towards first-principles predictions of concentrations and temperatureintervals where the alloy decomposition proceeds via the spinodal mechanism.We thus calculate electronic structure, lattice parameter, and mixing enthalpiesof the quasibinary alloy c-Ti1−xAlxN. The lattice parameter follows Vegard'slaw at low fractions of AlN but deviates increasingly withincreasing Al content. We show that the asymmetry of themixing enthalpy and its second concentration derivative is associated withsubstantial variations of the electronic structure with alloy composition. Thephase diagram is constructed within the mean-field approximation.

  • 46.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Shallcross, Sam
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb2006Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, nr 6, s. 064418-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first material to be predicted from first-principles calculations as half-metallic was NiMnSb, and the research on this material has been intense due to its possible applications in spintronics devices. The failure of many experiments to measure spin polarization to more than a fraction of the predicted 100% has partly been blamed on structural defects. In this work a complete first-principles treatise of point defects, including nonstoichiometric antisites, interstitial and vacancy defects, as well as stoichiometric atomic swap defects in NiMnSb, is presented. We find that the formation energies of the defects span a large scale from 0.2 to 14.4 eV. The defects with low formation energies preserve the half-metallic character of the material. We also find that some of the defects increase the magnetic moment and thus can explain the experimentally observed increase of magnetic moments in some samples of NiMnSb. Most interesting in this respect are Mn interstitials which increase the magnetic moment, have a low formation energy, and keep the half-metallic character of the material.

  • 47.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Steneget, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tholander, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Configurational disorder effects on adatom mobilities on Ti1-xAlxN(001) surfaces from first principles2012Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 24, s. 245422-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use metastable NaCl-structure Ti0.5Al0.5N alloys to probe effects of configurational disorder on adatom surface diffusion dynamics which control phase stability and nanostructural evolution during film growth. First-principles calculations were employed to obtain energy potential maps of Ti and Al adsorption on an ordered TiN(001) reference surface and a disordered Ti0.5Al0.5N(001) solid-solution surface. The energetics of adatom migration on these surfaces are determined and compared to isolate effects of configurational disorder. The results show that alloy surface disorder dramatically reduces Ti adatom mobilities. Al adatoms, in sharp contrast, experience only small disorder-induced differences in migration dynamics.

  • 48.
    Almyras, Georgios
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide Giuseppe
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Ruhr Univ Bochum, Germany.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanodesign. Linköpings universitet, Tekniska fakulteten.
    Semi-Empirical Force-Field Model For The Ti1-XAlXN (0 ≤ x ≤ 1) System2019Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 2, artikkel-id 215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a modified embedded atom method (MEAM) semi-empirical force-field model for the Ti1-xAlxN (0 x 1) alloy system. The MEAM parameters, determined via an adaptive simulated-annealing (ASA) minimization scheme, optimize the models predictions with respect to 0 K equilibrium volumes, elastic constants, cohesive energies, enthalpies of mixing, and point-defect formation energies, for a set of approximate to 40 elemental, binary, and ternary Ti-Al-N structures and configurations. Subsequently, the reliability of the model is thoroughly verified against known finite-temperature thermodynamic and kinetic properties of key binary Ti-N and Al-N phases, as well as properties of Ti1-xAlxN (0 amp;lt; x amp;lt; 1) alloys. The successful outcome of the validation underscores the transferability of our model, opening the way for large-scale molecular dynamics simulations of, e.g., phase evolution, interfacial processes, and mechanical response in Ti-Al-N-based alloys, superlattices, and nanostructures.

  • 49.
    Andersson, D.A.
    et al.
    KTH.
    Simak, Sergey
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Johansson, B.
    KTH, och Uppsala universitet.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Skorodumova, N.V.
    Uppsala universitet.
    Modeling of CeO2, Ce2O3, and CeO2−x in the LDA+U formalism2007Inngår i: Physical review. B, Condensed matter and materials physics, Vol. 75, s. 035109-1-035109-6Artikkel i tidsskrift (Fagfellevurdert)
  • 50.
    Andersson, D.A.
    et al.
    KTH.
    Simak, Sergey
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Skorodumova, N.V.
    Uppsala universitet.
    Abrikosov, Igor
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Johansson, B.
    KTH, och Uppsala universitet.
    Redox properties of CeO2-MO2 (M=Ti, Zr, Hf, or Th) solid solutions from first principles calculations2007Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, s. 31909-1-31919-3Artikkel i tidsskrift (Fagfellevurdert)
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