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基于第一性原理计算方法系统地研究了L21和B2结构下的Heusler合金Co2MnAl(100)表面原子的原子弛豫、电子结构、磁性和自旋极化行为. L21和B2结构的Co2MnAl(100)表面由于Co–Mn和Co–Al的成键差异, 使得不同原子分别发生不同程度的伸缩. 与块体相比, Co和Mn原子的自旋磁矩由于表面效应而明显增大, 电子结构计算显示L21结构块体中的带隙被表面态破坏, 表面效应使得两种结构的CoCo端面自旋极化率降低, 但MnAl端面并未受到显著影响, 呈现了较大的自旋极化, 预测其在隧道结中可能具有很好的应用潜力.Using the first-principles calculations within the generalized gradient approximation frame work, we systematically investigate the atomic relaxation, electronic structure, magnetism, and spin-polarization in L21 and B2 structure of Heusler alloy Co2MnAl (100) surface. Due to the difference of Co–Mn and Co–Al bonding, surface atoms in the L21 and B2 structure prefer to move toward and away from the vacuum. By comparison with the bulk, the spin magnetic moments of surface Co and Mn atoms are obviously enhanced due to the surface effects. Our electronic structure calculations show that the gap in L21 structure of bulk Co2MnAl has been destroyed by the surface states and the spin-polarization of CoCo atomic terminated surface in both structures decreases. However, the spin-polarization of MnAl atomic terminated surface is not significantly affected by the surface effects and has a large value in both structures, and this may be the potential in application to magnetic tunneling junctions.
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Keywords:
- Heusler alloy /
- surface /
- spin-polarization /
- magnetism
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[6] Miura Y, Uchida H, Oba Y, Abe K, Shirai M 2008 Phys. Rev. B 78 064416
[7] Khosravizadeh Sh, Hashemifar S J, Akbarzadeh H 2009 Phys. Rev. B 79 235203
[8] Sakuma A, Toga Y, Tsuchiura H 2009 J. Appl. Phys. 105 07C910
[9] Ishida S, Masaki T, Fujii S, Asano S 1998 Physica B 245 1
[10] Kubota H, Nakata J, Oogane M, Ando Y, Sakuma A, Miyazaki T 2004 Jpn. J. Appl. Phys. 243 L984
[11] Umetsu R Y, Kobayashi K, Fujita A, Kainuma R, Ishida K 2008 J. Appl. Phys. 103 07D718
[12] Vinesh A, Sudheesh V D, Lakshmi N, Venugopalan K 2014 AIP Conference Proceedings 1591 1521
[13] Alhaj B A, Hamad B 2012 J. Appl. Phys. 112 123904
[14] Tung J C, Guo G Y 2013 New J. Phys. 15 033014
[15] Sakuraba Y, Kokado S, Hirayama Y, Furubayashi T, Sukegawa H, Li S, Takahashi Y K, Hono K 2014 Appl. Phys. Lett. 104 172407
[16] Blochl P E 1994 Phys. Rev. B 50 17953
[17] Kresse G, Joubert D 1999 Phys. Rev. B 59 1758
[18] Kresse G, Furthmuller J 1996 Phys. Rev. B 54 11169
[19] Kresse G, Furthmuller J 1996 Comput. Mater. Sci. 6 15
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[1] de Groot R A, Mueller F M, van Engen P G, Bushow K H J 1983 Phys. Rev. Lett. 50 2024
[2] Kübler J, Williams R A, Sommers C B 1983 Phys. Rev. B 28 1745
[3] Galanakis I, Dederichs P H, Papanikolaou N 2002 Phys. Rev. B 66 174429
[4] Hasnip P J, Smith J H, Lazarov V K 2013 J. Appl. Phys. 113 17B106
[5] Kallmayer M, Schneider H, Jakob G, Elmers H J, Balke B, Cramm S 2007 J. Phys. D: Appl. Phys. 40 1552
[6] Miura Y, Uchida H, Oba Y, Abe K, Shirai M 2008 Phys. Rev. B 78 064416
[7] Khosravizadeh Sh, Hashemifar S J, Akbarzadeh H 2009 Phys. Rev. B 79 235203
[8] Sakuma A, Toga Y, Tsuchiura H 2009 J. Appl. Phys. 105 07C910
[9] Ishida S, Masaki T, Fujii S, Asano S 1998 Physica B 245 1
[10] Kubota H, Nakata J, Oogane M, Ando Y, Sakuma A, Miyazaki T 2004 Jpn. J. Appl. Phys. 243 L984
[11] Umetsu R Y, Kobayashi K, Fujita A, Kainuma R, Ishida K 2008 J. Appl. Phys. 103 07D718
[12] Vinesh A, Sudheesh V D, Lakshmi N, Venugopalan K 2014 AIP Conference Proceedings 1591 1521
[13] Alhaj B A, Hamad B 2012 J. Appl. Phys. 112 123904
[14] Tung J C, Guo G Y 2013 New J. Phys. 15 033014
[15] Sakuraba Y, Kokado S, Hirayama Y, Furubayashi T, Sukegawa H, Li S, Takahashi Y K, Hono K 2014 Appl. Phys. Lett. 104 172407
[16] Blochl P E 1994 Phys. Rev. B 50 17953
[17] Kresse G, Joubert D 1999 Phys. Rev. B 59 1758
[18] Kresse G, Furthmuller J 1996 Phys. Rev. B 54 11169
[19] Kresse G, Furthmuller J 1996 Comput. Mater. Sci. 6 15
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