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运用第一性原理的方法,计算磁性形状记忆合金Mn2NiGe的晶体结构、磁结构、 电子结构在马氏体相变中的变化.结果表明: Mn2NiGe在发生马氏体相变时, 产生了c轴拉长而a和b轴缩短的Jahn-Teller畸变,形成一个由两根长键和四根短键 组成的拉长的八面体;伴随Jahn-Teller畸变,处于八面体中心的Mn离子的磁矩发生了显著的变化, 而作为配体的Ni和Ge离子的磁矩基本不变; Jahn-Teller效应中Mn离子的eg和t2g 能级的分裂,源自于晶体畸变所产生的配位场的改变,导致Mn离子d电子态密度的重新分布, 从而在费米能级两侧打开一个赝能隙.
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关键词:
- Mn2NiGe /
- 马氏体相变 /
- 带Jahn-Teller效应 /
- 第一性原理
The changes of crystal structure, magnetic structure, electronic structure in the martensitic phase transition for magnetic shape memory alloy Mn2NiGe are calculated by first-principles method. The results show that in the martensitic phase transition for Mn2NiGe, there is produced a Jahn-Teller distortion, in which the c-axis becomes longer but a-axis and b-axis turn shorter, forming an elongated octahedral geometry. There is a significant change in magnetic moment for Mn ion in the centre of octahedron, but a little change happens to the Ni and Ge ions that are regarded as a ligand. The energy levels of eg and t2g are split by redistributing the density of states for d electrons and so opening a pseudogap near the fermi energy due to lattice distortion.-
Keywords:
- Mn2NiGe /
- martensitic phase transition /
- band Jahn-Teller effect /
- first-principles
[1] Wan J F, Wang J N 2005 Physica B 355 172
[2] Bernard F, Rousselot C, Hirsinger L, Delobelle P 2007 Plasma Proc. Polym. 4 S846
[3] Jakob G, Elmers H J 2007 J. Magn. Magn. Mater. 310 2779
[4] Zheng H X, Liu J, Xia M X, Li J G 2005 J. Alloys Compd. 387 265
[5] Aich S, Das S, Al-Omari I A, Alagarsamy P, Chowdhury S G, Chakraborty M, Shield J E, Sellmyer D J 2009 J. Appl. Phys. 105 07A943
[6] Tetsuji S, Yukihiko K, Toshiro K 2008 J. Appl. Phys. 103 07B322
[7] Liu Z H, Yu S Y, Yang H, Wu G H, Liu Y 2008 Intermetallics 16 447
[8] Moya X, Mañosa L, Planes A, Krenke T, Acet M, Wassermann E F 2006 Mater. Sci. Eng. A 438-440 911
[9] Liu G D, Dai X F, Yu S Y, Zhu Z Y, Chen J L, Wu G H 2006 Phys. Rev. B: Condens. Matter 74 054435
[10] Luo L J, Zhong C G, Quan H R, Tan Z Z, Jiang Q, Jiang X F 2010 Acta Phys. Sin. 59 8037 (in Chinese) [罗礼进, 仲崇贵, 全宏瑞, 谭志中, 蒋青, 江学范 2010 物理学报 59 8037]
[11] Xu Z Y 1999 Martensitic Transformation and Martensite (Beijing: Science Press) (in Chinese) [徐祖耀 1999 马氏体相变与马氏体(北京:科学出版社)]
[12] Vasil'ev A N, Bozhko A D, Khovailo V V 1999 Phys. Rev. B 59 1113
[13] Labbe J, Friedel J 1966 J. Phys. 27 153
[14] Zayak A T, Entel P, Enkovaara J, Ayuela A, Nieminen R M 2003 Phys. Rev. B 68 132402
[15] Suits J C 1976 Solid State Commun. 18 423
[16] Fujii S, Ishida S, Asano S 1989 J. Phys. Soc. Jpn. 58 3657
[17] Brown P J, Bargawi A Y, Crangle J, Neumann K U, Ziebeck K R A 1999 J. Phys.: Condens. Matter 11 4715
[18] Yin M T, Cohen Marvin L 1982 Phys. Rev. B 26 5668
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[1] Wan J F, Wang J N 2005 Physica B 355 172
[2] Bernard F, Rousselot C, Hirsinger L, Delobelle P 2007 Plasma Proc. Polym. 4 S846
[3] Jakob G, Elmers H J 2007 J. Magn. Magn. Mater. 310 2779
[4] Zheng H X, Liu J, Xia M X, Li J G 2005 J. Alloys Compd. 387 265
[5] Aich S, Das S, Al-Omari I A, Alagarsamy P, Chowdhury S G, Chakraborty M, Shield J E, Sellmyer D J 2009 J. Appl. Phys. 105 07A943
[6] Tetsuji S, Yukihiko K, Toshiro K 2008 J. Appl. Phys. 103 07B322
[7] Liu Z H, Yu S Y, Yang H, Wu G H, Liu Y 2008 Intermetallics 16 447
[8] Moya X, Mañosa L, Planes A, Krenke T, Acet M, Wassermann E F 2006 Mater. Sci. Eng. A 438-440 911
[9] Liu G D, Dai X F, Yu S Y, Zhu Z Y, Chen J L, Wu G H 2006 Phys. Rev. B: Condens. Matter 74 054435
[10] Luo L J, Zhong C G, Quan H R, Tan Z Z, Jiang Q, Jiang X F 2010 Acta Phys. Sin. 59 8037 (in Chinese) [罗礼进, 仲崇贵, 全宏瑞, 谭志中, 蒋青, 江学范 2010 物理学报 59 8037]
[11] Xu Z Y 1999 Martensitic Transformation and Martensite (Beijing: Science Press) (in Chinese) [徐祖耀 1999 马氏体相变与马氏体(北京:科学出版社)]
[12] Vasil'ev A N, Bozhko A D, Khovailo V V 1999 Phys. Rev. B 59 1113
[13] Labbe J, Friedel J 1966 J. Phys. 27 153
[14] Zayak A T, Entel P, Enkovaara J, Ayuela A, Nieminen R M 2003 Phys. Rev. B 68 132402
[15] Suits J C 1976 Solid State Commun. 18 423
[16] Fujii S, Ishida S, Asano S 1989 J. Phys. Soc. Jpn. 58 3657
[17] Brown P J, Bargawi A Y, Crangle J, Neumann K U, Ziebeck K R A 1999 J. Phys.: Condens. Matter 11 4715
[18] Yin M T, Cohen Marvin L 1982 Phys. Rev. B 26 5668
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