First-principles investigation of phonon softenings and lattice instabilities in the shape-memory system Ni2MnGa
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© 2003 American Physical Society (APS). This is the accepted version of the following article: Zayak, A. T. & Entel, P. & Enkovaara, J. & Ayuela, A. & Nieminen, Risto M. 2003. First-principles investigation of phonon softenings and lattice instabilities in the shape-memory system Ni2MnGa. Physical Review B. Volume 68, Issue 13. 132402/1-4. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.68.132402, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.68.132402.
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School of Science |
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2003
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Mcode
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Language
en
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132402/1-4
Series
Physical Review B, Volume 68, Issue 13
Abstract
Ferromagnetic Ni2MnGa has unique magnetoelastic properties. These are investigated by detailed computational studies of the phonon-dispersion curves for the non-modulated cubic L21 and tetragonal structures. For the L21 structure, a complete softening of the transverse-acoustic mode has been found around the wave vector q=[1/3,1/3,0](2π/a). The softening of this TA2 phonon mode leads to the premartensitic modulated superstructure observed experimentally. Further phonon anomalies, related to other structural transformations in Ni2MnGa, have also been found and examined. These anomalies appear to be due to the coupling of particular acoustic-phonon modes and optical modes derived from Ni.Description
Keywords
ferromagnetic Ni2MnGa, magnetoelastic properties
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Citation
Zayak, A. T. & Entel, P. & Enkovaara, J. & Ayuela, A. & Nieminen, Risto M. 2003. First-principles investigation of phonon softenings and lattice instabilities in the shape-memory system Ni2MnGa. Physical Review B. Volume 68, Issue 13. 132402/1-4. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.68.132402.