liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct 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
Configurational and Magnetic Interactions in Multicomponent Systems
Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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

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

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

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

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

Place, publisher, year, edition, pages
Linköping: Linköpings Universitet , 2010. , 98 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1334
Keyword [en]
Magnetic interactions, Configurational thermodynamics, Curie temperature, theoretical physics, magnetism, TiAlN, TiN, AlN, CrN, TiCrN, nitrides, NiMnSb, NiCuMnSb, Heusler alloys, spintronics, half-metallic, spinodal decomposition, first-principles, ab-initio
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:liu:diva-60446ISBN: 978-91-7393-330-8 (print)OAI: oai:DiVA.org:liu-60446DiVA: diva2:356676
Public defence
2010-09-09, Planck, Fysikhuset, Campus Valla, Linköping University, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2010-11-17 Created: 2010-10-13 Last updated: 2016-08-31Bibliographically approved
List of papers
1. Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb
Open this publication in new window or tab >>Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb
2006 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 73, no 6, 064418- p.Article in journal (Refereed) Published
Abstract [en]

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

Keyword
nickel alloys, manganese alloys, antimony alloys, ferromagnetic materials, ab initio calculations, interstitials, antisite defects, vacancies (crystal), defect states, magnetic moments
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-35025 (URN)10.1103/PhysRevB.73.064418 (DOI)24646 (Local ID)24646 (Archive number)24646 (OAI)
Note
Original Publication: Björn Alling, Sam Shallcross and Igor Abrikosov, Role of stoichiometric and nonstoichiometric defects on the magnetic properties of the half-metallic ferromagnet NiMnSb, 2006, Physical Review B. Condensed Matter and Materials Physics, (73), 6, 064418. http://dx.doi.org/10.1103/PhysRevB.73.064418 Copyright: American Physical Society http://www.aps.org/ Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
2.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
3.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
4. Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys
Open this publication in new window or tab >>Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys
Show others...
2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 1, 014434- p.Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
American Physical Society, 2007
Keyword
Iron alloys, nickel alloys, ferromagnetic materials, magnetic structure, ab initio calculations, density functional theory, linear muffin-tin orbital method, local moments
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-14277 (URN)10.1103/PhysRevB.76.014434 (DOI)
Note
Original Publication: Igor A. Abrikosov, Andreas E. Kissavos, Francois Liot, Björn Alling, Sergey Simak, O. Peil and A. V. Ruban, Competition between Magnetic Structures in the Fe-Rich FCC FeNi Alloys, 2007, Physical Review B Condensed Matter, (76), 1, 014434. http://dx.doi.org/10.1103/PhysRevB.76.014434 Copyright: American Physical Society http://www.aps.org/Available from: 2007-02-01 Created: 2007-02-01 Last updated: 2017-12-13Bibliographically approved
5. Questionable collapse of the bulk modulus in CrN
Open this publication in new window or tab >>Questionable collapse of the bulk modulus in CrN
2010 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 9, no 4, 283-284 p.Article in journal, Letter (Other academic) Published
Abstract [en]

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

Place, publisher, year, edition, pages
London, UK: Nature Publishing Group, 2010
Keyword
CrN, phase-transition, magnetism, bulk modulus, first-principles
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-60438 (URN)10.1038/nmat2722 (DOI)000275901000002 ()
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2017-12-12Bibliographically approved
6. Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN
Open this publication in new window or tab >>Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, 184430- p.Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
American institute of physics, 2010
Keyword
CrN, magnetic disorder, nitrides, LDA+U, SQS, phase transition, chromium compounds
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-60439 (URN)10.1103/PhysRevB.82.184430 (DOI)000291462500005 ()
Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2017-12-12
7. Theory of the ferromagnetism in Ti1-xCrxN solid solutions
Open this publication in new window or tab >>Theory of the ferromagnetism in Ti1-xCrxN solid solutions
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 5, 054408- p.Article in journal (Refereed) Published
Abstract [en]

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

Keyword
TiN, CrN, TiCrN, solid solutions, first-principles, magnetic interactions, ferromagnetism, electronic structure
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-60441 (URN)10.1103/PhysRevB.82.054408 (DOI)
Note
Original Publication: Björn Alling, Theory of the ferromagnetism in Ti1-xCrxN solid solutions, 2010, Physical Review B Condensed Matter, (82), 5, 054408. http://dx.doi.org/10.1103/PhysRevB.82.054408 Copyright: American Physical Society http://www.aps.org/Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2017-12-12
8. A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN
Open this publication in new window or tab >>A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN
Show others...
2011 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 83, no 10, 104203- p.Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
American Physical Society, 2011
Keyword
TiAlN, TiN, AlN, cluster expansion, GPM, spinodal decomposition, first-principles, titanium aluminium nitride, clustering, phase separation
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-60442 (URN)10.1103/PhysRevB.83.104203 (DOI)000288782700004 ()
Note
Original Publication: Björn Alling, A. V. Ruban, A Karimi, Lars Hultman and Igor Abrikosov, A unified cluster expansion method applied to the configurational thermodynamics of cubic TiAlN, 2011, Physical Review B. Condensed Matter and Materials Physics, (83), 10, 104203. http://dx.doi.org/10.1103/PhysRevB.83.104203 Copyright: American Physical Society http://www.aps.org/ Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2017-12-12
9. Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN
Open this publication in new window or tab >>Pressure enhancement of the isostructural cubic decomposition in Ti1−xAlxN
2009 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, no 181906Article in journal (Refereed) Published
Abstract [en]

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

Keyword
ab initio calculations, aluminium compounds, enthalpy, high-pressure effects, mixing, solid solutions, spinodal decomposition, titanium compounds
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-51569 (URN)10.1063/1.3256196 (DOI)
Note
Original Publication: Björn Alling, Magnus Odén, Lars Hultman and Igor Abrikosov, Pressure enhancement of the isostructural cubic decomposition in Ti1-xAlxN, 2009, Applied Physics Letters, (95), 181906. http://dx.doi.org/10.1063/1.3256196 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2009-11-07 Created: 2009-11-07 Last updated: 2017-12-12
10. Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions
Open this publication in new window or tab >>Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions
Show others...
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 22, 224101- p.Article in journal (Refereed) Published
Abstract [en]

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

Keyword
TiAlN, ScAlN, spinodal decomposition, nitrides, TiN, ScN, AlN, XRD, TEM, first-principles, phase separation, meta stable
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-56270 (URN)10.1103/PhysRevB.81.224101 (DOI)000278300900004 ()
Note
Original Publication: Carina Höglund, Björn Alling, Jens Birch, Manfred Beckers, Per O. Å. Persson, Carsten Baehtz, Zsolt Czigány, Jens Jensen and Lars Hultman, Effects of volume mismatch and electronic structure on the decomposition of ScAlN and TiAlN solid solutions, 2010, Physical Review B. Condensed Matter and Materials Physics, (81), 22, 224101. http://dx.doi.org/10.1103/PhysRevB.81.224101 Copyright: American Physical Society http://www.aps.org/ Available from: 2010-05-06 Created: 2010-05-06 Last updated: 2017-12-12
11.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.

Open Access in DiVA

Configurational and Magnetic Interactions in Multicomponent Systems(2419 kB)1352 downloads
File information
File name FULLTEXT01.pdfFile size 2419 kBChecksum SHA-512
4a03dc22f208271132c4ed4c90620159a5ed4d5c3ff53f351fa8c0139c09115ea19193ec281c64373f77fe041304fd8070563a2ddc5e758b4852561e4f5a9d54
Type fulltextMimetype application/pdf
Cover(91 kB)213 downloads
File information
File name COVER01.pdfFile size 91 kBChecksum SHA-512
80526fdb7a37a90aaa97b46e6a57777af64aa3fc7b38bfceb0d1310f534cf6066c65b5f4200c92b79133fad2aa70f53b0ae6aa8aea80a9ff7ae1a8842158a114
Type coverMimetype application/pdf

Authority records BETA

Alling, Björn

Search in DiVA

By author/editor
Alling, Björn
By organisation
Theoretical PhysicsThe Institute of Technology
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 1352 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1579 hits
CiteExportLink to record
Permanent link

Direct 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