Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Poster I

MA 16.20: Poster

Dienstag, 12. März 2013, 10:30–13:30, Poster D

Spin-transfer torque in Fe/MgO/Fe-MTJs with perpendicular magnetic anisotropy — •Jia Zhang, Michael Crezner, and Christian Heiliger — I. Physikalisches Institut, Justus Liebig University, Giessen, Germany

Recently, it was shown that MgO based magnetic tunnel junctions (MTJs) with ultrathin CoFe magnetic electrodes can have perpendicular magnetic anisotropy (PMA) and a low current for current driven switching[1]. In this work, the perpendicular anisotropy and spin-transfer torque in Fe/MgO/Fe-MTJs with ultrathin magnetic Fe layers in the presence of spin-orbital coupling are investigated by full relativistic Korringa-Kohn-Rostoker (KKR) first-principles calculations[2]. First, the critical thickness of Fe with perpendicular anisotropy is determined by calculating the magnetic crystal anisotropy and the shape anisotropy. Second, the bias voltage and angular dependence of spin-transfer torques is calculated. It is found that spin-orbital coupling have three significant effects on the spin-transfer torque: (1) The PMA contributes a new out-plane pseudo-torque in addition to the interlayer exchange coupling torque. (2) The spin-orbital coupling greatly change the magnitude of the spin-transfer torque. (3) The tunneling anisotropy leads to a strong angular dependence of spin-transfer torque.

[1] S. Ikeda et al. Nature Mater. 9, 721(2010).

[2] C. Heiliger et al., Phys. Rev. Lett. 100, 186805 (2008) ; J. Appl. Phys. 103, 07A709 (2008)