First-principles investigation of phonon softenings and lattice instabilities in the shape-memory system Ni2MnGa -: art. no. 132402

被引：107

作者：

Zayak, AT ^{[1
]}

Entel, P

Enkovaara, J

Ayuela, A

Nieminen, RM

机构：

[1] Gerhard Mercator Univ, Inst Phys, D-47048 Duisburg, Germany

[2] Helsinki Univ Technol, Phys Lab, Espoo 02015, Finland

来源：

PHYSICAL REVIEW B | 2003年 / 68卷 / 13期

关键词：

D O I：

10.1103/PhysRevB.68.132402

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Ferromagnetic Ni2MnGa has unique magnetoelastic properties. These are investigated by detailed computational studies of the phonon-dispersion curves for the non-modulated cubic L2(1) and tetragonal structures. For the L2(1) structure, a complete softening of the transverse-acoustic mode has been found around the wave vector q=[1/3,1/3,0](2pi/a). The softening of this TA(2) 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.

引用

页数：4

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