Spin Injection into Graphene from Heusler Alloy Co₂MnGe (111) Surface: A First Principles Study

Abstract:

To obtain a larger spin signal for use in graphene-based spintronic devices, the spin injection efficiency needs to be enhanced. Previously researchers can increase the efficiency by inserting a tunnel barrier such as Al₂O₃ or MgO between ferromagnet and graphene. However, the key value in spin transport is still very low because of the conductance mismatch as well as the limit to fabricate a high-quality tunnel barrier at the junction surface. Here we use a highly spin-polarized ferromagnetic material—Heusler alloy Co₂MnGe as a substitutional scheme without the tunnel barrier. The spin injection efficiency of our Co₂MnGe (111)/graphene junction can be as high as 73% which is much higher than 1% of ferromagnet/graphene or 30% of ferromagnet/oxide/graphene using first-principles study. The large spin polarization can be explicated by analyzing the transmission spectrum at the nonequilibrium state.

• Periodical: Materials Science Forum (Volume 914)
• Pages: 111-116
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.914.111
• Online since: February 2018
• Authors: Ya Xin Wang*, Tong Sheng Xia
• Keywords: First Principle Study, Graphene, Heusler Alloy, Spin Injection, Spintronics

References

[1] H.J. Zhu, Ramsteiner M, Kostial H, et al. Room-temperature spin injection from Fe into GaAs [J]. Phys Rev Lett, 2001, 87(1): 016601.

DOI: 10.1103/physrevlett.87.016601

[2] Hanbicki A T, Jonker B T, Itskos G, et al. Efficient electrical spin injection from a magnetic metal/tunnel barrier contact into a semiconductor[J]. Applied Physics Letters, 2002, 81(11): 2131-2132.

DOI: 10.1063/1.1507361

[3] Yoh K, Ohno H, Katano Y, et al. Spin injection from a ferromagnetic electrode into InAs surface inversion layer[C]. International Conference on Molecular Beam Epitaxy. IEEE, 2002: 337-341.

DOI: 10.1109/mbe.2002.1037789

[4] Yoh K, Ohno H, Sueoka K, et al. Reduced interface reaction during the epitaxial Fe growth on InAs for high efficiency spin injection[J]. Journal of Vacuum Science & Technology B Microelectronics & Nanometer Structures, 2004, 22(3): 1432-1435.

DOI: 10.1116/1.1755711

[5] K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, Y. Zhang, S.V. Dubonos, I.V. Grigorieva, and A.A. Firsov, Science 306, 666 (2004).

DOI: 10.1126/science.1102896

[6] E.W. Hill, A.K. Geim, K. Novoselov, F. Schedin, and P. Blake, Graphene spin valve devices, IEEE Trans. Magn. 42, 2694 (2006).

DOI: 10.1109/tmag.2006.878852

[7] W. Han, K. Pi, W. Bao, K. M. McCreary, Y. Li, W.H. Wang, C.N. Lau, and R.K. Kawakami, Electrical detection of spin precession in single layer graphene spin valves with transparent contacts, Appl. Phys. Lett. 94, 222109(2009).

DOI: 10.1063/1.3147203

[8] G. Schmidt, D. Ferrand, L.W. Molenkamp, A.T. Filip, and B.J. van Wees, Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor, Phys. Rev. B 62, R4790 (2000).

DOI: 10.1103/physrevb.62.r4790

[9] H. Goto, A. Kanda, T. Sato, S. Tanaka, Y. Ootuka, S. Odaka, H. Miyazaki, K. Tsukagoshi, and Y. Aoyagi, Gate control of spin transport in multilayer graphene, Appl. Phys. Lett. 92, 212110 (2008).

DOI: 10.1063/1.2937836

[10] N. Tombros, C. Jozsa, M. Popinciuc, H.T. Jonkman, and B.J. van Wees, Electronic spin transport and spin precession in single graphene layers at room temperature, Nature (London) 448, 571 (2007).

DOI: 10.1038/nature06037

[11] W.H. Wang, K. Pi, Y. Li, Y.F. Chiang, P. Wei, J. Shi, and R.K. Kawakami, Phys. Rev. B 77, 020402 (2008).

[12] B. Dlubak, P. Seneor, A. Anane, C. Barraud, C. Deranlot, D. Deneuve, B. Servet, R. Mattana, F. Petroff, and A. Fert, Are Al2O3 and MgO tunnel barriers suitable for spin injection in graphene?, Appl. Phys. Lett. 97, 092502 (2010).

DOI: 10.1063/1.3476339

[13] R.A. de Groot, F.M. Mueller, P.G. van Engen, and K.H.J. Buschow, Phys. Rev. Lett. 50, 2024 (1983).

[14] S. Trudel, O. Gaier, J. Hamrle, and B. Hillebrands, J. Phys. D: Appl. Phys. 43, 193001 (2010).

DOI: 10.1088/0022-3727/43/19/193001

[15] Z.Y. Yao, Jun F U, Pan M M, et al. First-principles study on half-metallic and magnetic stability of Co_2 MnSi and Co_2 MnGe[J]. Journal of Atomic & Molecular Physics, 2009, 26(2): 252-256.

[16] I. Galandkis, and P. H. Dederichs, Phys. Rev. B, 2002, 66: 174429.

[17] H. Ibach and H. Luth, Solid State Physics, 2nd ed., Springer-Verlag, Berlin (1995).

[18] P. Hohenberg and W. Kohn, Phys. Rev., 1964, 136, B864;W. Kohn and L.J. Sham, ibid., 1965, 140, A1133.

[19] G. Kresse and J. Hafner, Phys. Rev. B, 1993, 47, 558.

[20] G. Kresse and D. Joubert, Phys. Rev. B: Condens. Matter Mater. Phys., 1999, 59, 1758.

[21] J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996).

[22] H. J. Monkhorst and J. D. Pack, Phys. Rev. B: Solid State, 1976, 13, 5188.

[23] Jauho A P, Wingreen N S, Meir Y. Time-dependent transport in interacting and noninteracting resonant-tunneling systems [J]. Physical Review B Condensed Matter, 1994, 50(8): 5528.

DOI: 10.1103/physrevb.50.5528

[24] Taylor J, Guo H, Wang J. Taylor, J. Guo, H. & Wang, J. Ab initio modeling of quantum transport properties of molecular electronic devices. Phys. Rev. B 63, 245407[J]. Physical Review B, 2001, 63(24).

DOI: 10.1103/physrevb.63.245407

[25] J. P. Perdew, Y. Wang, Phys. Rev. B, 1992, 45: 13244.

[26] J. P. Perdew, J. A. CHevary, S.H. Vosko, Phys. Rev B, 1992, 46: 6671.

[27] W. Han, K. Pi, K. M. McCreary, Y. Li, J. J. I. Wong, A. G. Swartz, and R. K. Kawakami, Tunneling spin injection into single layer graphene, Phys. Rev. Lett. 105, 167202(2010).

DOI: 10.1103/physrevlett.105.167202

[28] Yamaguchi T, Moriya R, Oki Y, et al. Spin injection into multilayer graphene from highly spin-polarized Co2FeSi Heusler alloy [J]. Applied Physics Express, 2016, 9(6): 063006.

DOI: 10.7567/apex.9.063006