liu.seSearch for publications in DiVA
Change search
Refine search result
12345 151 - 200 of 250
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151.
    Monteseguro, V
    et al.
    Univ Valencia, Spain; European Radiat Synchrotron Facil, France.
    Sans, J. A.
    Univ Politecn Valencia, Spain.
    Cuartero, V
    European Radiat Synchrotron Facil, France; Ctr Univ Def Zaragoza, Spain.
    Cova, F.
    European Radiat Synchrotron Facil, France.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Natl Univ Sci and Technol MISIS, Russia.
    Olovsson, Weine
    Linköping University, National Supercomputer Centre (NSC). Linköping University, Faculty of Science & Engineering.
    Popescu, C.
    ALBA CELLS, Spain.
    Pascarelli, S.
    European Radiat Synchrotron Facil, France.
    Garbarino, G.
    European Radiat Synchrotron Facil, France.
    Jönsson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Irifune, T.
    Ehime Univ, Japan; Tokyo Inst Technol, Japan.
    Errandonea, D.
    Univ Valencia, Spain.
    Phase stability and electronic structure of iridium metal at the megabar range2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 8940Article in journal (Refereed)
    Abstract [en]

    The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter. Synchrotron-based powder x-ray diffraction results highlight a large stability range (up to 1.4 Mbar) of the low-pressure phase. The compressibility behaviour was characterized by an accurate determination of the pressure-volume equation of state, with a bulk modulus of 339(3) GPa and its derivative of 5.3(1). X-ray absorption spectroscopy, which probes the local structure and the empty density of electronic states above the Fermi level, was also utilized. The remarkable agreement observed between experimental and calculated spectra validates the reliability of theoretical predictions of the pressure dependence of the electronic structure of iridium in the studied interval of compressions.

  • 152.
    Mosyagin, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia.
    Gambino, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Sangiovanni, Davide
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Ruhr Univ Bochum, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia.
    Caffrey, Nuala M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Trinity Coll Dublin, Ireland.
    Effect of dispersion corrections on ab initio predictions of graphite and diamond properties under pressure2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, no 17, article id 174103Article in journal (Refereed)
    Abstract [en]

    There are several approaches to the description of van der Waals (vdW) forces within density functional theory. While they are generally found to improve the structural and energetic properties of those materials dominated by weak dispersion forces, it is not known how they behave when the material is subject to an external pressure. This could be an issue when considering the pressure-induced structural phase transitions, which are currently attracting great attention following the discovery of an ultrahard phase formed by the compression of graphite at room temperature. In order to model this transition, the functional must be capable of simultaneously describing both strong covalent bonds and weak dispersion interactions as an isotropic pressure is applied. Here, we report on the ability of several dispersion-correction functionals to describe the energetic, structural, and elastic properties of graphite and diamond, when subjected to an isotropic pressure. Almost all of the tested vdW corrections provide an improved description of both graphite and diamond compared to the local density approximation. The relative error does not change significantly as pressure is applied, and in some cases even decreases. We therefore conclude that the use of dispersion-corrected exchange-correlation functionals, which have been neglected to date, will improve the accuracy and reliability of theoretical investigations into the pressure-induced phase transition of graphite.

  • 153.
    Mosyagin, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Olovsson, Weine
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia.
    Highly Efficient Free Energy Calculations of the Fe Equation of State Using Temperature-Dependent Effective Potential Method2016In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 120, no 43, p. 8761-8768Article in journal (Refereed)
    Abstract [en]

    Free energy calculations at finite temperature based on ab initio molecular dynamics (AIMD) simulations have become possible, but they are still highly computationally demanding. Besides, achieving simultaneously high accuracy of the calculated results and efficiency of the computational algorithm is still a challenge. In this work we describe an efficient algorithm to determine accurate free energies of solids in simulations using the recently proposed temperature-dependent effective potential method (TDEP). We provide a detailed analysis of numerical approximations employed in the TDEP algorithm. We show that for a model system considered in this work, hcp Fe, the obtained thermal equation of state at 2000 K is in excellent agreement with the results of standard calculations within the quasiharmonic approximation.

  • 154.
    Mosyagin, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia.
    Lugovskoy, A. V.
    NUST MISIS, Russia.
    Krasilnikov, O. M.
    NUST MISIS, Russia.
    Vekilov, Yu. Kh.
    NUST MISIS, Russia; NUST MISIS, Russia.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Ab initio calculations of pressure-dependence of high-order elastic constants using finite deformations approach2017In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 220, p. 20-30Article in journal (Refereed)
    Abstract [en]

    We present a description of a technique for ab initio calculations of the pressure dependence of second and third-order elastic constants. The technique is based on an evaluation of the corresponding Lagrangian stress tensor derivative of the total energy assuming finite size of the deformations. Important details and parameters of the calculations are highlighted. Considering body-centered cubic Mo as a model system, we demonstrate that the technique is highly customizable and can be used to investigate non-linear elastic properties under high-pressure conditions. (C) 2017 Elsevier B.V. All rights reserved.

  • 155.
    Mosyagin, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISTS, Russia.
    Lugovskoy, A. V.
    NUST MISTS, Russia.
    Krasilnikov, O. M.
    NUST MISTS, Russia; NUST MISTS, Russia.
    Vekilov, Yu. Kh.
    NUST MISTS, Russia; NUST MISTS, Russia.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Reply to the comment by M. Mazdziarz on the article "Ab initio calculations of pressure-dependence of high-order elastic constants using finite deformations approach" [Computer Physics Communications 220 (2017) 20-30]2019In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 235, p. 295-296Article in journal (Other academic)
    Abstract [en]

    Marcin Mazdziarz has published a comment on our recent paper by I. Mosyagin, A.V. Lugovskoy, O.M. Krasilnikov, Yu.Kh. Vekilov, S.I. Simak and L.A. Abrikosov titled "Ab initio calculations of pressure dependence of high-order elastic constants using finite deformations approach" [Computer Physics Communications 220 (2017)2030]. The author states that there are serious fundamental errors and flaws. In this reply we clarify all misunderstanding mentioned in the said comment. (C) 2018 Published by Elsevier B.V.

    The full text will be freely available from 2020-06-19 15:55
  • 156.
    Mozafari, Elham
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Max Planck Inst Eisenforsch GmbH, Germany.
    Belov, Maxim P.
    NUST MISIS, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Effect of the lattice dynamics on the electronic structure of paramagnetic NiO within the disordered local moment picture2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 3, article id 035152Article in journal (Refereed)
    Abstract [en]

    Using the disordered local moments approach in combination with the ab initio molecular dynamics method, we simulate the behavior of a paramagnetic phase of NiO at finite temperatures to investigate the effect of magnetic disorder, thermal expansion, and lattice vibrations on its electronic structure. In addition, we study its lattice dynamics. We verify the reliability of our theoretical scheme via comparison of our results with available experiment and earlier theoretical studies carried out within static approximations. We present the phonon dispersion relations for the paramagnetic rock-salt (B1) phase of NiO and demonstrate that it is dynamically stable. We observe that including the magnetic disorder to simulate the paramagnetic phase has a small yet visible effect on the band gap. The amplitude of the local magnetic moment of Ni ions from our calculations for both antiferromagnetic and paramagnetic phases agree well with other theoretical and experimental values. We demonstrate that the increase of temperature up to 1000 K does not affect the electronic structure strongly. Taking into account the lattice vibrations and thermal expansion at higher temperatures have amajor impact on the electronic structure, reducing the band gap from similar to 3.5 eV at 600 K to similar to 2.5 eV at 2000 K. We conclude that static lattice approximations can be safely employed in simulations of the paramagnetic state of NiO up to relatively high temperatures (similar to 1000 K), but as we get closer to the melting temperature vibrational effects become quite large and therefore should be included in the calculations.

  • 157.
    Mozafari, Elham
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. NUST MISIS, Russia; Tomsk State University, Russia.
    Role of N defects in paramagnetic CrN at finite temperatures from first principles2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 9, p. 094101-Article in journal (Refereed)
    Abstract [en]

    Simulations of defects in paramagnetic materials at high temperature constitute a formidable challenge to solid-state theory due to the interaction of magnetic disorder, vibrations, and structural relaxations. CrN is a material where these effects are particularly large due to a strong magnetolattice coupling and a tendency for deviations from the nominal 1: 1 stoichiometry. In this work, we present a first-principles study of nitrogen vacancies and nitrogen interstitials in CrN at elevated temperature. We report on formation energetics, the geometry of interstitial nitrogen dimers, and the impact on the electronic structure caused by the defects. We find a vacancy formation energy of 2.28 eV with a small effect of temperature, i.e., a formation energy for N interstitial in the form of a less than 111 greater than -oriented split bond of 3.77 eV with an increase to 3.97 at 1000 K. Vacancies are found to add three electrons, while split-bond interstitial adds one electron to the conduction band. The band gap of defect-free CrN is smeared out due to vibrations, although it is difficult to draw a conclusion about the exact temperature at which the band gap closes from our calculations. However, it is clear that at 900 K there is a nonzero density of electronic states at the Fermi level. At 300 K, our results indicate a border case where the band gap is about to close.

  • 158.
    Mozafari, Elham
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Shulumba, Nina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Materials Modeling and Development Laboratory, NUST “MISIS”, Moscow, Russia.
    Finite-temperature elastic constants of paramagnetic materials within the disordered local moment picture from ab initio molecular dynamics calculations2016In: Physical Review B, ISSN 2469-9950, Vol. 94, no 5, article id 054111Article in journal (Refereed)
    Abstract [en]

    We present a theoretical scheme to calculate the elastic constants of magnetic materials in the high-temperature paramagnetic state. Our approach is based on a combination of disordered local moments picture and ab initio molecular dynamics (DLM-MD). Moreover, we investigate a possibility to enhance the efficiency of the simulations of elastic properties using the recently introduced method: symmetry imposed force constant temperature-dependent effective potential (SIFC-TDEP). We have chosen cubic paramagnetic CrN as a model system. This is done due to its technological importance and its demonstrated strong coupling between magnetic and lattice degrees of freedom. We have studied the temperature-dependent single-crystal and polycrystalline elastic constants of paramagentic CrN up to 1200 K. The obtained results at T = 300 K agree well with the experimental values of polycrystalline elastic constants as well as the Poisson ratio at room temperature. We observe that the Young’s modulus is strongly dependent on temperature, decreasing by 14% from T = 300 K to 1200 K. In addition we have studied the elastic anisotropy of CrN as a function of temperature and we observe that CrN becomes substantially more isotropic as the temperature increases. We demonstrate that the use of Birch law may lead to substantial errors for calculations of temperature induced changes of elastic moduli. The proposed methodology can be used for accurate predictions of mechanical properties of magnetic materials at temperatures above their magnetic order-disorder phase transition.

  • 159.
    Mukhamedov, B. O.
    et al.
    National University of Science and Technology MISIS, Russia.
    Ponomareva, A. V.
    National University of Science and Technology MISIS, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Spinodal decomposition in ternary Fe-Cr-Co system2017In: JOURNAL OF ALLOYS AND COMPOUNDS, ISSN 0925-8388, Vol. 695, p. 250-256Article in journal (Refereed)
    Abstract [en]

    Using the exact muffin-tin orbitals method in conjunction with the coherent potential approximation we have studied the tendency towards spinodal decomposition of solid solution in ternary Fe-Cr-Co system. In addition, we have estimated the Curie temperature of the alloys, and considered the influence of the magnetic state on the decomposition thermodynamics of the ternary alloys. Using the mean field approximation, we have estimated the finite temperature effects on the alloys free energy. We predict that an increase Co and Cr content in the ternary Fe-Cr-Co system increases the tendency of the bcc (alpha)-FexCryCoz alloys towards the spinodal decomposition. Because of this, high magnetic properties and high thermal stability of these properties can be expected in the Fe-Cr-Co alloys with high Co content. (C) 2016 Elsevier B.V. All rights reserved.

  • 160.
    Mukhamedov, B. O.
    et al.
    Natl Univ Sci and Technol MISIS, Russia.
    Saenko, I
    Freiberg Univ Min and Technol, Germany; Russian Acad Sci, Russia.
    Ponomareva, A. V
    Natl Univ Sci and Technol MISIS, Russia.
    Kriegel, M. J.
    Freiberg Univ Min and Technol, Germany.
    Chugreev, A.
    Leibniz Univ Hannover, Germany.
    Udovsky, A.
    Russian Acad Sci, Russia; Natl Res Nucl Univ MEPhl, Russia.
    Fabrichnaya, O.
    Freiberg Univ Min and Technol, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Thermodynamic and physical properties of Zr3Fe and ZrFe2 intermetallic compounds2019In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 109, p. 189-196Article in journal (Refereed)
    Abstract [en]

    Experimental differential scanning calorimetry measurements and ab-initio simulations were carried out to define the heat capacities of Zr3Fe and C15-ZrFe2 compounds from 0 K up to their maximum stability temperatures. Experimental measurements of heat capacity of each compound were performed for the first time in wide range of temperatures. Density functional theory and quasi-harmonic approximation (QHA) were employed to calculate the free energy of the studied systems as a function of volume and temperature. A good agreement was observed between theoretical and experimental heat capacities within validity range of the QHA. This makes it possible to combine theoretical and experimental data to determine the standard entropies of intermetallic compounds.

    The full text will be freely available from 2021-04-03 08:54
  • 161.
    Music, Denis
    et al.
    Materials Chemistry, RWTH Aachen University, Germany.
    Takahashi, Tetsuya
    Materials Chemistry, RWTH Aachen University, Germany.
    Vitos, Levente
    Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Sweden.
    Asker Göransson, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Schneider, Jochen M.
    Materials Chemistry, RWTH Aachen University, Germany.
    Elastic properties of Fe–Mn random alloys studied by ab initio calculations2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 19, p. 191904-Article in journal (Refereed)
    Abstract [en]

    We have studied the influence of the Mn content on the elastic properties of Fe–Mn random alloys (space group of Fmm) using ab initio calculations. The magnetic effects in Fe–Mn alloys have a strong influence on the elastic properties, even above the Néel temperature. As the Mn content is increased from 5  to  40  at.  %, the C44 elastic constant is unaffected, while C11 and C12 decrease. This behavior can be understood based on the magnetovolume effect which softens the lattice. Since the amplitude of local magnetic moments is less sensitive to volume conserving distortions, the softening is not present during shearing.

  • 162.
    Ning, Weihua
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Tech Univ, Peoples R China.
    Zhao, Xin-Gang
    Jilin Univ, Peoples R China.
    Klarbring, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ji, Fuxiang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Tao, Youtian
    Nanjing Tech Univ, Peoples R China.
    Ren, Xiao-Ming
    Nanjing Tech Univ, Peoples R China.
    Zhang, Lijun
    Jilin Univ, Peoples R China.
    Huang, Wei
    Nanjing Tech Univ, Peoples R China.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Natl Univ Sci and Technol MISIS, Russia.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Thermochromic Lead-Free Halide Double Perovskites2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 10, article id 1807375Article in journal (Refereed)
    Abstract [en]

    Lead-free halide double perovskites with diverse electronic structures and optical responses, as well as superior material stability show great promise for a range of optoelectronic applications. However, their large bandgaps limit their applications in the visible light range such as solar cells. In this work, an efficient temperature-derived bandgap modulation, that is, an exotic fully reversible thermochromism in both single crystals and thin films of Cs2AgBiBr6 double perovskites is demonstrated. Along with the thermochromism, temperature-dependent changes in the bond lengths of Ag Symbol of the Klingon Empire Br (R-Ag Symbol of the Klingon Empire Br) and Bi Symbol of the Klingon Empire Br (R-Bi Symbol of the Klingon Empire Br) are observed. The first-principle molecular dynamics simulations reveal substantial anharmonic fluctuations of the R-Ag Symbol of the Klingon Empire Br and R-Bi Symbol of the Klingon Empire Br at high temperatures. The synergy of anharmonic fluctuations and associated electron-phonon coupling, and the peculiar spin-orbit coupling effect, is responsible for the thermochromism. In addition, the intrinsic bandgap of Cs2AgBiBr6 shows negligible changes after repeated heating/cooling cycles under ambient conditions, indicating excellent thermal and environmental stability. This work demonstrates a stable thermochromic lead-free double perovskite that has great potential in the applications of smart windows and temperature sensors. Moreover, the findings on the structure modulation-induced bandgap narrowing of Cs2AgBiBr6 provide new insights for the further development of optoelectronic devices based on the lead-free halide double perovskites.

    The full text will be freely available from 2020-01-20 15:10
  • 163.
    Norrby, Niklas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Lind, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Parakhonskiy, G
    University of Bayreuth, Germany .
    Johansson, M P.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Dubrovinsky, L S.
    University of Bayreuth, Germany .
    Dubrovinskaia, N
    University of Bayreuth, Germany .
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    High pressure and high temperature stabilization of cubic AlN in Ti0.60Al0.40N2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 5Article in journal (Refereed)
    Abstract [en]

    In the present work, the decomposition of unstable arc evaporated Ti0.6Al0.4N at elevated temperatures and quasihydrostatic pressures has been studied both experimentally and by first-principles calculations. High pressure and high temperature (HPHT) treatment of the samples was realized using the multi anvil press and diamond anvil cell techniques. The products of the HPHT treatment of Ti0.6Al0.4N were investigated using x-ray diffractometry and transmission electron microscopy. Complimentary calculations show that both hydrostatic pressure and high temperature stabilize the cubic phase of AlN, which is one of the decomposition products of Ti0.6Al0.4N. This is in agreement with the experimental results which in addition suggest that the presence of Ti in the system serves to increase the stability region of the cubic c-AlN phase. The results are industrially important as they show that Ti0.6Al0.4N coatings on cutting inserts do not deteriorate faster under pressure due to the cubic AlN to hexagonal AlN transformation.

  • 164.
    Nuala, Mai Caffrey
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia; Tomsk State University, Russia.
    Charge neutrality in epitaxial graphene on 6H-SiC(0001) via nitrogen intercalation2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 8, article id 081409Article in journal (Refereed)
    Abstract [en]

    The electronic properties of epitaxial graphene grown on SiC(0001) are known to be impaired relative to those of freestanding graphene. This is due to the formation of a carbon buffer layer between the graphene layers and the substrate, which causes the graphene layers to become strongly n-doped. Charge neutrality can be achieved by completely passivating the dangling bonds of the clean SiC surface using atomic intercalation. So far, only one element, hydrogen, has been identified as a promising candidate. We show, using first-principles density functional calculations, how it can also be accomplished via the growth of a thin layer of silicon nitride on the SiC surface. The subsequently grown graphene layers display the electronic properties associated with charge neutral graphene. We show that the surface energy of this structure is considerably lower than that of others with intercalated atomic nitrogen and determine how its stability depends on the N-2 chemical potential.

  • 165.
    Nuala, M.Caffrey
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Johansson, Leif I
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Xia, Chao
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia; Tomsk State University, Russia.
    Jacobi, Chariya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Structural and electronic properties of Li-intercalated graphene on SiC(0001)2016In: Physical Review B: covering condensed matter and materials physics, ISSN 2469-9950, Vol. 93, no 19, p. 195421-1-195421-9Article in journal (Refereed)
    Abstract [en]

    We investigate the structural and electronic properties of Li-intercalated monolayer graphene on SiC(0001) using combined angle-resolved photoemission spectroscopy and first-principles density functional theory. Li intercalates at room temperature both at the interface between the buffer layer and SiC and between the two carbon layers. The graphene is strongly n-doped due to charge transfer from the Li atoms and two pi bands are visible at the (K) over bar point. After heating the sample to 300 degrees C, these pi bands become sharp and have a distinctly different dispersion to that of Bernal-stacked bilayer graphene. We suggest that the Li atoms intercalate between the two carbon layers with an ordered structure, similar to that of bulk LiC6. An AA stacking of these two layers becomes energetically favourable. The pi bands around the (K) over bar point closely resemble the calculated band structure of a C6LiC6 system, where the intercalated Li atoms impose a superpotential on the graphene electronic structure that opens gaps at the Dirac points of the two pi cones.

  • 166.
    Olovsson, W.
    et al.
    Uppsala University.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Variation of the effective exchange parameter across 3d-transition metal series2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 10Article in journal (Refereed)
    Abstract [en]

    The so-called effective exchange parameter J0 of the classical Heisenberg Hamiltonian for magnetic interactions is investigated as a function of volume and occupation of the valence band across 3d-transition-metal series in face-centered-cubic (fcc) metals, from Mn to Ni. We show that there exists a particular area in the volume-electron concentration phase space, where the effective exchange parameter behaves anomalously. The peculiarity, in combination with deviations of the electronic structure in real alloys from the rigid-band behavior, should lead to highly frustrated magnetic configurations that were predicted theoretically for the fcc Invar alloys.

  • 167. Olovsson, W
    et al.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Variation of the effective exchange parameter across 3d-transition-metal series2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 10Article in journal (Refereed)
    Abstract [en]

    The so-called effective exchange parameter J(0) of the classical Heisenberg Hamiltonian for magnetic interactions is investigated as a function of volume and occupation of the valence band across 3d-transition-metal series in face-centered-cubic (fcc) metals, from Mn to Ni. We show that there exists a particular area in the volume-electron concentration phase space, where the effective exchange parameter behaves anomalously. The peculiarity, in combination with deviations of the electronic structure in real alloys from the rigid-band behavior, should lead to highly frustrated magnetic configurations that were predicted theoretically for the fcc Invar alloys. (c) 2005 American Institute of Physics.

  • 168.
    Olovsson, W.
    et al.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-757 21 Uppsala, Sweden.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Johansson, B.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-757 21 Uppsala, Sweden, Applied Materials Physics, Dept. of Mat. Sci. and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Newton, A.
    Department of Physics, Surface Science Research Center, University of Liverpool, Liverpool L69 3BX, United Kingdom.
    Cole, R.J.
    Department of Physics, Ctr. for Mat. Sci. and Engineering, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom.
    Weightman, P.
    Department of Physics, Surface Science Research Center, University of Liverpool, Liverpool L69 3BX, United Kingdom.
    Auger energy shifts in fcc AgPd random alloys from complete screening picture and experiment2004In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, no 22, p. 226406-1Article in journal (Refereed)
    Abstract [en]

    The Auger kinetic energy and Auger parameter shifts in fcc AgPd random alloys were calculated by extending the complete screening picture. The auger kinetic energy shift for the L3M4,5M4,5 Auger transition was calculated ab initio and compared with first-principles calculations. The shifts were analyzed as a function of alloy compositions. The Auger kinetic energy shifts were also analyzed in terms of single-hole states for the 2p3/2 core level and double-hole states for the 3d 5/2 core level.

  • 169.
    Olovsson, W.
    et al.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Bech, L.
    Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg East, Denmark.
    Andersen, T.H.
    Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
    Li, Z.
    Institute of Storage Ring Facilities, University of Aarhus, DK-8000 Aarhus C, Denmark.
    Hoffmann, S.V.
    Institute of Storage Ring Facilities, University of Aarhus, DK-8000 Aarhus C, Denmark.
    Johansson, B.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden, Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Onsgaard, J.
    Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg East, Denmark.
    Core-level shifts for two- and three-dimensional bimetallic Pdx Cu1-x and Pdx Ag1-x alloys on Ru(0001)2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 7Article in journal (Refereed)
    Abstract [en]

    Core-level binding energy shifts (CLSs) and surface CLS (SCLSs) are determined by experiment and theory for ultrathin Pd as well as for PdCu and PdAg surface alloys which vary in thickness from 1 to 4 monolayers (MLs), supported on Ru(0001). Experimentally, the binding energies of Pd and Ag 3 d5 2 are measured by photoelectron spectroscopy using synchrotron radiation, and in the case of Cu 2 p3 2 by x rays (XPS) from a Mg Ka radiation source. The calculations are based on first-principles techniques together with the complete screening picture, including initial and final state effects directly in the same scheme. Dimensional as well as temperature effects are observed and reproduced theoretically, with a good agreement between the calculated CLS and the experimentally observed values. Further it is demonstrated how the layer composition profile of a 4 ML thick PdAg film can be followed by comparing theoretical layer specific CLSs with the measured ones and combine this with the observed intensities of the Ag 3 d5 2 photoelectrons. © 2005 The American Physical Society.

  • 170.
    Olovsson, W.
    et al.
    Condensed Matter Theory Group, Department of Physics, Uppsala University.
    Göransson Asker, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Pourovskii, L. V.
    Department of Theoretical Physics, University of Nijmegen, The Netherlands.
    Johansson, B.
    Condensed Matter Theory Group, Department of Physics, Uppsala University.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Core-level shifts in fcc random alloys: A first-principles approach2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 6, p. 064203-Article in journal (Refereed)
    Abstract [en]

    First-principles theoretical calculations of the core-level binding-energy shift (CLS) for eight binary face-centered-cubic (fcc) disordered alloys, CuPd, AgPd, CuNi, NiPd, CuAu, PdAu, CuPt, and NiPt, are carried out within density-functional theory (DFT) using the coherent potential approximation. The shifts of the Cu and Ni 2p3∕2, Ag and Pd 3d5∕2, and Pt and Au 4f7∕2 core levels are calculated according to the complete screening picture, which includes both initial-state (core-electron energy eigenvalue) and final-state (core-hole screening) effects in the same scheme. The results are compared with available experimental data, and the agreement is shown to be good. The CLSs are analyzed in terms of initial- and final-state effects. We also compare the complete screening picture with the CLS obtained by the transition-state method, and find very good agreement between these two alternative approaches for the calculations within the DFT. In addition the sensitivity of the CLS to relativistic and magnetic effects is studied.

  • 171.
    Olovsson, W.
    et al.
    Uppsala University.
    Holmström, E.
    Los Alamos National Laboratory, New Mexico, USA.
    Wills, J.
    Los Alamos National Laboratory, New Mexico, USA.
    James, P.
    SKF Group MDC, Göteborg.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Niklasson, A.M.N.
    Los Alamos National Laboratory, New Mexico, USA.
    Relationship between the electronic structure of embedded single to triple atomic monolayers and bulk alloys2005In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 72, no 15, p. 5419-Article in journal (Refereed)
    Abstract [en]

    The relation between the electronic structure of thin film nanosandwiches and bulk alloys has been investigated by means of first-principles electronic structure theory. The spin magnetization, layered projected spectral properties, and interface core-level shifts of Cu, Ni, Co, and Fe systems have been calculated. In order to compare thin films to bulk alloys, systems with equal average nearest-neighbor coordination have been compared. We find that the spin magnetization and interface core level shifts are closely related to bulk with the exception of the core level shifts in the Fe/Cu multilayers, which are more sensitive to the specific structure of the thin film geometry. The discrepancy is discussed in terms of interacting interface states in the Cu spacer. The experimental possibility of detecting embedded monolayers is also investigated. © 2005 The American Physical Society.

  • 172.
    Olovsson, Weine
    et al.
    Kyoto University, Sakyo Kyoto.
    Asker, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Marten, Tobias
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Core-level shifts in complex metallic systems from first principle2006In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 243, no 11, p. 2447-2464Article in journal (Refereed)
    Abstract [en]

    We show that core-level binding energy shifts (CLS) can be reliably calculated within density functional theory. The scheme includes both the initial (electron energy eigenvalue) as well as final state (relaxation due to core-hole screening) effects in the same framework. The results include CLS as a function of composition in substitutional random bulk and surface alloys. Sensitivity of the CLS to the local chemical environment in the bulk and at the surface is demonstrated. A possibility to use the CLS for structural determination is discussed. Finally, an extension of the model is made for Auger kinetic energy shift calculations.

  • 173.
    Olovsson, Weine
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Holmstroem, Erik
    University Austral Chile.
    Marten, Tobias
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Niklasson, Anders M N
    Los Alamos National Laboratory.
    Interface core-level shifts as a probe of embedded thin-film quality2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 8, p. 085431-Article in journal (Refereed)
    Abstract [en]

    We use first-principles calculations of layer-resolved core-level binding energy shifts (CLSs) within density functional theory as away to characterize the interface quality and thickness in embedded thin-film nanomaterials. A closer study of interfaces is motivated as properties specific to nanostructures can be related directly to the interface environment or indirectly as interference effects due to quantum confinement. From an analysis based on the Cu 2p(3/2) CLS for Cu embedded in Ni and Co fcc (100) and Fe bcc (100), with the interfaces represented by intermixing profiles controlled by a single parameter, we evaluate layer-resolved shifts as a probe of the thin-film quality. The core-level shifts in the corresponding disordered alloys, as well as local environment effects, are studied for comparison. We also discuss the possibility of detecting interface states by means of core-level shift measurements.

  • 174.
    Olovsson, Weine
    et al.
    Department of Materials Science and Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
    Marten, Tobias
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Holmstrom, Erik
    Instituto de Física, Universidad Austral de Chile, Valdivia, Chile.
    Johansson, Borje
    Department of Physics and Materials Science, Uppsala University, P.O. Box 530, SE-751 21 Uppsala, Sweden.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    First principle calculations of core-level binding energy and Auger kinetic energy shifts in metallic solids2010In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 178, no Sp. Iss. SI, p. 88-99Article in journal (Refereed)
    Abstract [en]

    We present a brief overview of recent theoretical studies of the core-level binding energy shift (CLS) in solid metallic materials. The focus is on first principles calculations using the complete screening picture, which incorporates the initial (ground state) and final (core-ionized) state contributions of the electron photoemission process in X-ray photoelectron spectroscopy (XPS), all within density functional theory (DFT). Considering substitutionally disordered binary alloys, we demonstrate that on the one hand CLS depend on average conditions, such as volume and overall composition, while on the other hand they are sensitive to the specific local atomic environment. The possibility of employing layer resolved shifts as a tool for characterizing interface quality in fully embedded thin films is also discussed, with examples for CuNi systems. An extension of the complete screening picture to core-core-core Auger transitions is given, and new results for the influence of local environment effects on Auger kinetic energy shifts in fcc AgPd are presented.

  • 175.
    Olsson, P.
    et al.
    Dept Matériaux et Mécanique des Composants Electricité de France.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Wallenius, J.
    Dept of Neutron Research Uppsala University.
    Electronic origin of the anomalous stability of Fe-rich bcc Fe-Cr alloys2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, p. 104416-1-104416-8Article in journal (Refereed)
  • 176.
    Pakhomova, Anna
    et al.
    DESY, Germany.
    Aprilis, Georgios
    Univ Bayreuth, Germany.
    Bykov, Maxim
    Univ Bayreuth, Germany.
    Gorelova, Liudmila
    St Petersburg State Univ, Russia.
    Krivovichev, Sergey S.
    St Petersburg State Univ, Russia; Russian Acad Sci, Russia.
    Belov, Maxim P.
    NUST MISIS, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Penta- and hexa-coordinated beryllium and phosphorus in high-pressure modifications of CaBe2P2O82019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 2800Article in journal (Refereed)
    Abstract [en]

    Beryllium oxides have been extensively studied due to their unique chemical properties and important technological applications. Typically, in inorganic compounds beryllium is tetrahedrally coordinated by oxygen atoms. Herein based on results of in situ single crystal X-ray diffraction studies and ab initio calculations we report on the high-pressure behavior of CaBe2P2O8, to the best of our knowledge the first compound showing a step-wise transition of Be coordination from tetrahedral (4) to octahedral (6) through trigonal bipyramidal (5). It is remarkable that the same transformation route is observed for phosphorus. Our theoretical analysis suggests that the sequence of structural transitions of CaBe2P2O8 is associated with the electronic transformation from predominantly molecular orbitals at low pressure to the state with overlapping electronic clouds of anions orbitals.

  • 177.
    Palonen, H.
    et al.
    Uppsala Univ, Sweden.
    Mukhamedov, B. O.
    Natl Univ Sci and Technol MISIS, Russia.
    Ponomareva, A. V.
    Natl Univ Sci and Technol MISIS, Russia.
    Palsson, G. K.
    Uppsala Univ, Sweden.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Hjorvarsson, B.
    Uppsala Univ, Sweden.
    The magnetization profile induced by the double magnetic proximity effect in an Fe/Fe0.30V0.70 superlattice2019In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 115, no 1, article id 012406Article in journal (Refereed)
    Abstract [en]

    The double magnetic proximity effect (MPE) in an Fe/Fe0.30V0.70 superlattice is studied by a direct measurement of the magnetization profile using polarized neutron reflectivity. The experimental magnetization profile is shown to qualitatively agree with a profile calculated using density functional theory. The profile is divided into a short range interfacial part and a long range tail. The interfacial part is explained by charge transfer and induced magnetization, while the tail is attributed to the inhomogeneous nature of the FeV alloy. The long range tail in the magnetization persists up to 170% above the intrinsic ordering temperature of the FeV alloy. The observed effects can be used to design systems with a direct exchange coupling between layers over long distances through a network of connected atoms. When combined with the recent advances in tuning and switching, the MPE with electric fields and currents, the results can be applied in spintronic devices. Published under license by AIP Publishing.

  • 178.
    Pilch, Iris
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Caillault, L.
    University of Paris 11, France.
    Minea, T.
    University of Paris 11, France.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Tal, Alexey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Münger, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Brenning, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. KTH Royal Institute Technology, Sweden.
    Nanoparticle growth by collection of ions: orbital motion limited theory and collision-enhanced collection2016In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 39, p. 395208-Article in journal (Refereed)
    Abstract [en]

    The growth of nanoparticles in plasma is modeled for situations where the growth is mainly due to the collection of ions of the growth material. The model is based on the classical orbit motion limited (OML) theory with the addition of a collision-enhanced collection (CEC) of ions. The limits for this type of model are assessed with respect to three processes that are not included: evaporation of the growth material, electron field emission, and thermionic emission of electrons. It is found that both evaporation and thermionic emission can be disregarded below a temperature that depends on the nanoparticle material and on the plasma parameters; for copper in our high-density plasma this limit is about 1200 K. Electron field emission can be disregarded above a critical nanoparticle radius, in our case around 1.4 nm. The model is benchmarked, with good agreement, to the growth of copper nanoparticles from a radius of 5 nm-20 nm in a pulsed power hollow cathode discharge. Ion collection by collisions contributes with approximately 10% of the total current to particle growth, in spite of the fact that the collision mean free path is four orders of magnitude longer than the nanoparticle radius.

  • 179.
    Ponomareva, A. V.
    et al.
    National University of Science and Technology MISIS, Russia .
    Gornostyrev, Yu. N.
    Institute Quantum Mat Science, Russia Russian Academic Science, Russia .
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ab initio calculation of the solution enthalpies of substitutional and interstitial impurities in paramagnetic fcc Fe2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 1, p. 014439-Article in journal (Refereed)
    Abstract [en]

    In the framework of disordered local moment approach by using magnetic sampling method, we suggested a model that takes into account the magnetic disorder in paramagnetic Fe with point defects. We calculate solution enthalpies of substitutional (Nb, V) and interstitial (C, N) impurities in paramagnetic face-centered cubic Fe and obtain results that are in agreement with available experimental data. It is found that both interstitial and substitutional atoms may favor the local magnetic polarization of the Fe host around the impurities by decreasing the potential energy of the system. The possibility of a formation of predominantly ferromagnetic Fe clusters around carbon in the temperature range of overcooled austenite is discussed.

  • 180.
    Ponomareva, A. V.
    et al.
    National University of Science and Technology, Russia.
    Gornostyrev, Yu. N.
    Institute Quantum Mat Science, Russia; Russian Academic Science, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology, Russia.
    Energy of interaction between carbon impurities in paramagnetic gamma-iron2015In: Journal of Experimental and Theoretical Physics, ISSN 1063-7761, E-ISSN 1090-6509, Vol. 120, no 4, p. 716-724Article in journal (Refereed)
    Abstract [en]

    The energies of interaction between carbon impurity atoms in paramagnetic fcc iron (austenite) are calculated using electron density functional theory. Point defects in the paramagnetic matrix are described using a statistical approach that takes into account local magnetic fluctuations and atomic relaxation in the environment of impurity atoms. It is shown that, in addition to local deformations, magnetism significantly contributes to the energies of dissolution and interaction of carbon atoms. The values of the carbon-carbon interaction energy are indicative of a significant repulsion between these atoms in the first and second coordination spheres. The results of calculations are consistent with estimates obtained from experimental data on the activity of carbon impurity atoms in iron.

  • 181.
    Ponomareva, A V
    et al.
    National University of Science and Technology MISIS.
    Isaev, Eyvas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Kh Vekilov, Yu
    National University of Science and Technology MISIS.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Site preference and effect of alloying on elastic properties of ternary B2 NiAl-based alloys2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 14, p. 144117-Article in journal (Refereed)
    Abstract [en]

    Using the exact muffin-tin orbitals method in conjunction with the coherent potential approximation, we study the site preference of transition metal impurities X (X = Sc, Ti, V, Cr, W, Re, Co) in B2 NiAl and their effect on its elastic properties. Analyzing interatomic bonding of NiAl-X alloys and elastic characteristics evaluated from the elastic constants C-11, C-12, and C-44, we predict that the addition of W, V, Ti, and Re atoms could yield improved ductility for B2 NiAl-X alloys without significant changes in the macroscopic elastic moduli.

  • 182.
    Ponomareva, A V
    et al.
    National University of Science and Technology MISIS, Russia .
    Kh Vekilov, Yu
    National University of Science and Technology MISIS, Russia .
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Effect of Re content on elastic properties of B2 NiAl from ab initio calculations2014In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 586, p. S274-S278Article in journal (Refereed)
    Abstract [en]

    The effect of substitutional alloying of Re on elastic properties of B2 NiAl has been studied using first-principles electronic-structure calculations by the exact muffin-tin orbitals method and the coherent potential approximation. Our calculations have shown that elastic constants C-12, C-44 and bulk modulus B of (Ni1-xRex) Al alloys increase with Re composition almost linearly, but concentration dependence of elastic constants C-11, Young modulus E, shear modulus G, G/B ratio and the Cauchy pressure P-C is strongly nonmonotonously and has peculiarities near the concentration x = 30 at.% Re. Analyzing the density of states and Fermi surface sections we have a direct connection between the behavior of the elastic constants of (Ni1-xRex) Al alloys and changes in the interatomic bonding and Fermi surface topology.

  • 183.
    Ponomareva, A V
    et al.
    Moscow State Institute Steel & Alloys.
    Ruban, A V
    Royal Institute Technology.
    Dubrovinskaia, N
    University of Heidelberg.
    Dubrovinsky, L
    University of Bayreuth.
    Abrikosov , Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Influence of global magnetic state on chemical interactions in high-pressure high-temperature synthesis of B2 Fe2Si2009In: APPLIED PHYSICS LETTERS, ISSN 0003-6951 , Vol. 94, no 18, p. 181912-Article in journal (Refereed)
    Abstract [en]

    We show that effective chemical interactions in an alloy can be tuned by its global magnetic state, which opens exciting possibilities for materials synthesis. Using first-principles theory we demonstrate that at pressure of 20 GPa and at high temperatures, the effective chemical interactions in paramagnetic Fe-Si system are strongly influenced by the magnetic disorder favoring a formation of cubic Fe2Si phase with B2 structure, which is not present in the alloy phase diagram. Our experiments confirm theoretical predictions, and the B2 Fe2Si alloy is synthesized from Fe-Si mixture using multianvil press.

  • 184.
    Ponomareva, A. V.
    et al.
    Natl Univ Sci and Technol MISIS, Russia.
    Ruban, A. V.
    KTH Royal Inst Technol, Sweden; Leoben Forsch GmbH, Austria.
    Mukhamedov, B. O.
    Natl Univ Sci and Technol MISIS, Russia.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Effect of multicomponent alloying with Ni, Mn and Mo on phase stability of bcc Fe-Cr alloys2018In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 150, p. 117-129Article in journal (Refereed)
    Abstract [en]

    Fe-Cr system attracts lot of attention in condensed matter physics due to its technological importance and extraordinary physics related to a non-trivial interplay between magnetic and chemical interactions. However, the effect of multicomponent alloying on the properties of Fe-Cr alloys are less studied. We have calculated the mixing enthalpy, magnetic moments, effective chemical, strain-induced and magnetic exchange interactions to investigate the alloying effect of Ni, Mn, Mo on the phase stability of the ferromagnetic bcc Fe Cr system at zero K. We demonstrate that the alloying reduces the stability of Fe-Cr alloys and expands the region of spinodal decomposition. At the same time, the mixing enthalpy in ternary Fe100-c-05CrcNi05 alloys indicates a stability of solid solution phase up to 6 at. % Cr. In Fem(100-c-07)CrNi(05)Mn(01)Mo(01) alloys, we did not find any alloy composition that has negative enthalpy of formation. Analyzing magnetic and electronic properties of the alloys and investigating magnetic, chemical and strain-induced interactions in the studied systems, we provide physically transparent picture of the main factors leading to the destabilization of the Fe-Cr solid solutions by the multicomponent alloying with Ni, Mn, Mo. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    The full text will be freely available from 2020-03-15 13:27
  • 185.
    Ponomareva, A V
    et al.
    National University Sof cience and Technology MISIS.
    Ruban, A V
    Royal Institute of Technology.
    Vekilova, Olga
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Effect of pressure on phase stability in Fe-Cr alloys2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, no 9, p. 094422-Article in journal (Refereed)
    Abstract [en]

    The effect of hydrostatic pressure on the phase stability of Fe-Cr alloys has been studied using ab initio methods. We show that while pressure decreases the tendency toward the phase separation in the paramagnetic state of bcc alloys, in the ferromagnetic state it reduces the alloy stability at low Cr concentration and vice versa, makes the solid solution more stable at higher concentrations. This behavior of the phase stability can be predicted from the deviation of the lattice parameter from Vegards law in bcc Fe-Cr alloys. On the atomic level, the pressure effect can be explained by the suppression of the local magnetic moments on Cr atoms, which gives rise to a decrease of the Fe-Cr magnetic exchange interaction at the first coordination shell and, as a result, to the observed variation of the ordering tendency between the Fe and Cr atoms.

  • 186.
    Ponomareva, A.V.
    et al.
    Department of Theoretical Physics, Moscow Stt. Inst. of Stl. and Alloys, Leninskii prospect 4, Moscow 119991, Russian Federation.
    Isaev, E.I.
    Department of Theoretical Physics, Moscow Stt. Inst. of Stl. and Alloys, Leninskii prospect 4, Moscow 119991, Russian Federation.
    Pourovskii, L.V.
    Department of Physics, Uppsala University, Uppsala SE-751 21, Sweden, Department of Theoretical Physics, University of Nijmegen, Nijmegen 6500 GL, Netherlands.
    Vekilov, Yu.Kh.
    Department of Theoretical Physics, Moscow Stt. Inst. of Stl. and Alloys, Leninskii prospect 4, Moscow 119991, Russian Federation.
    Johansson, B.
    Department of Physics, Uppsala University, Uppsala SE-751 21, Sweden, Dept. of Mat. Sci. and Engineering, Royal Institute of Technology, Stockholm SE-100 44, Sweden.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Ab initio investigations of surface magnetism in V-Mo2004In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 272-276, p. 1198-1200Article in journal (Refereed)
    Abstract [en]

    Magnetic properties of the (0 0 1) surface of pure vanadium and disordered binary Mo-V alloys have been investigated from the first-principles by means of the LMTO-GF-CPA technique, the fixed spin moment method, and the direct exchange Monte-Carlo statistical mechanics simulations. The binary alloys, as well as pure constituent metals, are nonmagnetic in the bulk. However, we have shown that the (1 0 0) surface of uniformly random and segregated Mo-V alloys is magnetic. The magnetism of the V monolayer on the Mo(0 0 1) surface has also been studied. In particular, the surface relaxation effect has resulted in a reduction of the magnetic moments for V atoms, but the surface magnetism is still present in the system. Including of semi-core states as valence ones does not alter this conclusion. © 2004 Elsevier B.V. All rights reserved.

  • 187.
    Ponomareva, A.V.
    et al.
    Moscow Steel and Alloys Institute Moscow, Russia.
    Isaev, E.I.
    Moscow steel and Alloys Institute Moscow, Russia.
    Skorodumova, N.v.
    uppsala University, Uppsala.
    Vekilov, Yu. Kh.
    Moscow Steel and alloys Institute, Moscow Russia.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Surface segregation energy in bcc Fe-rich Fe-Cr alloys2007In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 75, no 24, p. 5406-Article in journal (Refereed)
    Abstract [en]

    The exact muffin-tin orbitals (EMTO) technique in conjunction with the coherent-potential approximation (CPA) as well as the projector-augmented-wave (PAW) method have been used to calculate the surface segregation energy of Cr at the (100) surface of Fe-rich bcc Fe-Cr alloys. We find that PAW results strongly depend on the supercell size used in the calculations. In particular, for large supercells, the surface segregation energy of Cr is positive, which means that Cr should not segregate toward the surface of diluted alloys. This is in agreement with our EMTO-CPA results as well as previous surface Green's-function calculations. However, the surface segregation energy of Cr is negative if small unit cells are used for simulations. This is in agreement with previous full-potential supercell calculations. We explain such a size dependence by a peculiar concentration dependence of interatomic interactions in ferromagnetic Fe-Cr alloys. © 2007 The American Physical Society.

  • 188.
    Potapkin, V.
    et al.
    Forschungszentrum Julich, Germany.
    Dubrovinsky, L.
    University of Bayreuth, Germany.
    Sergueev, I.
    DESY, Germany.
    Ekholm, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Kantor, I.
    European Synchrotron Radiat Facil, France.
    Bessas, D.
    European Synchrotron Radiat Facil, France.
    Bykova, E.
    University of Bayreuth, Germany.
    Prakapenka, V.
    University of Chicago, IL 60437 USA.
    Hermann, R. P.
    Forschungszentrum Julich, Germany; Oak Ridge National Lab, TN 37831 USA.
    Rueffer, R.
    European Synchrotron Radiat Facil, France.
    Cerantola, V.
    University of Bayreuth, Germany.
    Jönsson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Olovsson, W.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Mankovsky, S.
    University of Munich, Germany.
    Ebert, H.
    University of Munich, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia; Tomsk State University, Russia.
    Magnetic interactions in NiO at ultrahigh pressure2016In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, no 20, p. 201110-Article in journal (Refereed)
    Abstract [en]

    Magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV Mossbauer transition of Ni-61. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to similar to 24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distorted sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.

  • 189.
    Pourovskii, L V.
    et al.
    Ecole Polytech, France.
    Miyake, T
    AIST, Japan.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Ruban, A V.
    Royal Institute Technology, Sweden.
    Dubrovinsky, L
    University of Bayreuth, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Electronic properties and magnetism of iron at the Earth's inner core conditions2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 11Article in journal (Refereed)
    Abstract [en]

    We employ state-of-the-art ab initio simulations within the dynamical mean-field theory to study three likely phases of iron (hcp, fcc, and bcc) at the Earth's core conditions. We demonstrate that the correction to the electronic free energy due to correlations can be significant for the relative stability of the phases. The strongest effect is observed in bcc Fe, which shows a non-Fermi-liquid behavior, and where a Curie-Weiss behavior of the uniform susceptibility hints at a local magnetic moment still existing at 5800 K and 300 GPa. We predict that all three structures have sufficiently high magnetic susceptibility to stabilize the geodynamo.

  • 190.
    Pourovskii, L. V.
    et al.
    Univ Paris Saclay, France; Coll France, France; Natl Univ Sci and Technol MISIS, Russia.
    Mravlje, J.
    Jozef Stefan Inst, Slovenia.
    Georges, A.
    Univ Paris Saclay, France; Coll France, France; Univ Geneva, Switzerland.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Natl Univ Sci and Technol MISIS, Russia.
    Correction: Electron-electron scattering and thermal conductivity of epsilon-iron at Earths core conditions (vol 19, 073022, 2017)2018In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 20, article id 109501Article in journal (Refereed)
    Abstract [en]

    n/a

  • 191.
    Pourovskii, L. V.
    et al.
    University of Paris Saclay, France; Coll France, France; National University of Science and Technology MISIS, Russia.
    Mravlje, J.
    Jozef Stefan Institute, Slovenia.
    Georges, A.
    University of Paris Saclay, France; Coll France, France; University of Geneva, Switzerland.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Electron-electron scattering and thermal conductivity of epsilon-iron at Earths core conditions2017In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 19, article id 073022Article in journal (Refereed)
    Abstract [en]

    The electronic state and transport properties of hot dense iron are of the utmost importance for the understanding of Earths interior. Combining state-of-the-art density functional and dynamical mean field theories we study the impact of electron correlations on the electrical and thermal resistivity of hexagonal close-packed epsilon-Fe at Earths core conditions and show that the electron-electron scattering in epsilon-Fe exhibit a nearly perfect Fermi-liquid (FL) behavior. Accordingly, the quadratic dependence of the scattering rate, typical of FLs, leads to a modification of the Wiedemann-Franz law and suppresses the thermal conductivity with respect to the electrical one. The consequence is a significant increase of the electron-electron thermal resistivity, which is found to be of comparable magnitude to the electron-phonon one.

  • 192.
    Pourovskii, Leonid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. École Polytechnique, Palaiseau, France.
    Mravlje, J.
    Jozef Stefan Institute, Ljubljana, Slovenija.
    Ferrero, M.
    École Polytechnique, Palaiseau, France.
    Parcollet, O.
    Institut de Physique Théorique (IPhT), CEA, CNRS, URA 2306, Gif-sur-Yvette, France.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Impact of electronic correlations on the equation of state and transport in epsilon-Fe2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 15, p. 155120-Article in journal (Refereed)
    Abstract [en]

    We have obtained the equilibrium volumes, bulk moduli, and equations of state of the ferromagnetic cubic alpha and paramagnetic hexagonal epsilon phases of iron in close agreement with experiment using an ab initio dynamical mean-field-theory approach. The local dynamical correlations are shown to be crucial for a successful description of the ground-state properties of paramagnetic epsilon-Fe. Moreover, they enhance the effective mass of the quasiparticles and reduce their lifetimes across the alpha -greater than epsilon transition, leading to a stepwise increase of the resistivity, as observed in experiment. The calculated magnitude of the jump is significantly underestimated, which points to nonlocal correlations. The implications of our results for the superconductivity and non-Fermi-liquid behavior of epsilon-Fe are discussed.

  • 193. Pourovskii, L.V.
    et al.
    Ruban, A.V.
    Vitos, L.
    Ebert, H.
    Johansson, B.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Fully relativistic spin-polarized exact muffin-tin-orbital method2005In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 71, no 9Article in journal (Refereed)
    Abstract [en]

    The exact muffin-tin-orbital (EMTO) method is generalized for fully relativistic (FR) spin-polarized calculations. In the present implementation we solve self-consistently the four-component Dirac equation by using the Green's function formalism. Substitutional disorder is treated within the coherent potential approximation. To obtain accurate total energies we use the full-charge density technique. We apply the FR-EMTO Green's function method to calculate the ground-state properties of δ-Pu. We also calculate spin and orbital magnetic moments in random bcc, fcc, and hcp Fe-Co alloys, as well as in the B2 ordered and partially ordered phase. ©2005 The American Physical Society.

  • 194.
    Raza, Zamaan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia; Tomsk State University, Russia.
    Computer simulations of glasses: the potential energy landscape2015In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 29, p. 293201-Article, review/survey (Refereed)
    Abstract [en]

    We review the current state of research on glasses, discussing the theoretical background and computational models employed to describe them. This article focuses on the use of the potential energy landscape (PEL) paradigm to account for the phenomenology of glassy systems, and the way in which it can be applied in simulations and the interpretation of their results. This article provides a broad overview of the rich phenomenology of glasses, followed by a summary of the theoretical frameworks developed to describe this phenomonology. We discuss the background of the PEL in detail, the onerous task of how to generate computer models of glasses, various methods of analysing numerical simulations, and the literature on the most commonly used model systems. Finally, we tackle the problem of how to distinguish a good glass former from a good crystal former from an analysis of the PEL. In summarising the state of the potential energy landscape picture, we develop the foundations for new theoretical methods that allow the ab initio prediction of the glass- forming ability of new materials by analysis of the PEL.

  • 195.
    Raza, Zamaan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Shulumba, Nina
    Linköping University, Department of Physics, Chemistry and Biology. University of Saarland, Germany.
    Nuala, Mai Caffrey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Dubrovinsky, Leonid
    University of Bayreuth, Germany.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. NUST MISIS, Russia; Tomsk State University, Russia.
    First-principles calculations of properties of orthorhombic iron carbide Fe7C3 at the Earths core conditions2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 21, article id 214112Article in journal (Refereed)
    Abstract [en]

    A recently discovered phase of orthorhombic iron carbide o-Fe7C3 [Prescher et al., Nat. Geosci. 8, 220 (2015)] is assessed as a potentially important phase for interpretation of the properties of the Earths core. In this paper, we carry out first-principles calculations on o-Fe7C3, finding properties to be in broad agreement with recent experiments, including a high Poissons ratio (0.38). Our enthalpy calculations suggest that o-Fe7C3 is more stable than Eckstrom-Adcock hexagonal iron carbide (h-Fe7C3) below approximately 100 GPa. However, at 150 GPa, the two phases are essentially degenerate in terms of Gibbs free energy, and further increasing the pressure towards Earths core conditions stabilizes h-Fe7C3 with respect to the orthorhombic phase. Increasing the temperature tends to stabilize the hexagonal phase at 360 GPa, but this trend may change beyond the limit of the quasiharmonic approximation.

  • 196.
    Reeh, S
    et al.
    Rhein Westfal TH Aachen, Germany .
    Kasprzak, M
    Rhein Westfal TH Aachen, Germany .
    Klusmann, C D.
    Rhein Westfal TH Aachen, Germany .
    Stalf, F
    Rhein Westfal TH Aachen, Germany .
    Music, D
    Rhein Westfal TH Aachen, Germany .
    Ekholm, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Schneider, J M.
    Rhein Westfal TH Aachen, Germany .
    Elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys studied by the combinatorial thin film approach and ab initio calculations2013In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 24Article in journal (Refereed)
    Abstract [en]

    The elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys with additions of up to 8 at.% X were studied by combinatorial thin film growth and characterization and by ab initio calculations using the disordered local moments (DLM) approach. The lattice parameter and Youngs modulus values change only marginally with X. The calculations and experiments are in good agreement. We demonstrate that the elastic properties of transition metal alloyed Fe-Mn can be predicted by the DLM model.

  • 197.
    Reeh, S.
    et al.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Music, D.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Ekholm, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Schneider, J. M.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Elastic properties of fcc Fe-Mn-X (X=Cr, Co, Ni, Cu) alloys from first-principles calculations2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 22Article in journal (Refereed)
    Abstract [en]

    The influence of the valence electron concentration of X in fcc Fe-Mn-X (X=Cr, Co, Ni, Cu) alloys on the elastic and magnetic properties has been studied by means of ab initio calculations for alloy element concentrations of up to 8 at. % X. We observe that Cu increases the bulk-to-shear modulus (B/G) ratio by 19.2%. Simultaneously magnetic moments of Fe and Mn increase strongly. The other alloying elements induce less significant changes in B/G. The trends in B/G may be understood by considering the changes in G induced by the variation in valence electron concentration (VEC). As the VEC is increased, more pronounced metallic bonds are formed, giving rise to smaller shear modulus values. The changes in magnetic moments may be explained by the magnetovolume effect. Alloys with smaller VEC as Fe-Mn exhibit a decrease in local magnetic moments and equilibrium lattice parameters, while alloys with larger VEC as Fe-Mn demonstrate an increase in local magnetic moments and equilibrium lattice parameters. These data provide the basis for the design of Mn-rich steels with enhanced elastic properties.

  • 198.
    Ruban, A.V.
    et al.
    Department of Materials Science and Engineering Royal Institute of Technology.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Configurational thermodynamics of alloys from first principles: effective cluster interactions2008In: Reports on progress in physics (Print), ISSN 0034-4885, E-ISSN 1361-6633, Vol. 71, p. 046501-046529Article in journal (Refereed)
  • 199.
    Ruban, A.V.
    et al.
    Department of Materials Science and Engineering Royal Institute of Technology, Stockholm.
    Katsnelson, M.I.
    Institute for Molecules and Materials Radboud University Nijmegen, The Netherlands.
    Olovsson, W.
    Condensed Matter Theory Group, Department of Physics Uppsala University.
    Simak, S.I.
    Condensed Matter Theory Group, Department of Physics Uppsala University.
    Abrikosov, Igor
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Origin of magnetic frustrations in Fe-Ni Invar alloys2005In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 71, no 5, p. 4402-Article in journal (Refereed)
    Abstract [en]

    Pair exchange parameters Jij of the classical Heisenberg Hamiltonian for magnetic interactions in the urchetypical Invar system, face centered cubic (fee) Fe-Ni alloys, are calculated from the first principles. The magnetic structure of Fe-Ni alloys in the region of volumes and electron concentrations related to the Invar effect is highly frustrated. However, the origin of such a frustration in concentrated alloys and in the pure fee Fe are different. While in Fe it is due to the long-range oscillating Jij, in alloys with high Ni concentration it is mainly the consequence of a huge dispersion of the nearest-neighbor exchange parameters, caused by the local environment effects. ©2005 The American Physical Society.

  • 200.
    Sangiovanni, Davide
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. National University of Science and Technology, Russia; Tomsk State University, Russia.
    Nitrogen vacancy, self-interstitial diffusion, and Frenkel-pair formation/dissociation in B1 TiN studied by ab initio and classical molecular dynamics with optimized potentials2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 5, p. 054301-Article in journal (Refereed)
    Abstract [en]

    We use ab initio and classical molecular dynamics (AIMD and CMD) based on the modified embedded-atom method (MEAM) potential to simulate diffusion of N vacancy and N self-interstitial point defects in B1 TiN. TiN MEAM parameters are optimized to obtain CMD nitrogen point-defect jump rates in agreement with AIMD predictions, as well as an excellent description of TiNx (similar to 0.7 less than x less than= 1) elastic, thermal, and structural properties. We determine N dilute-point-defect diffusion pathways, activation energies, attempt frequencies, and diffusion coefficients as a function of temperature. In addition, the MD simulations presented in this paper reveal an unanticipated atomistic process, which controls the spontaneous formation of N self-interstitial/N vacancy (N-I/N-V) pairs (Frenkel pairs), in defect-free TiN. This entails that the N lattice atom leaves its bulk position and bonds to a neighboring N lattice atom. In most cases, Frenkel-pair N-I and N-V recombine within a fraction of ns; similar to 50% of these processes result in the exchange of two nitrogen lattice atoms (N-N-Exc). Occasionally, however, Frenkel-pair N-interstitial atoms permanently escape from the anion vacancy site, thus producing unpaired N-I and N-V point defects.

12345 151 - 200 of 250
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf