First principles investigation of magnetocrystalline anisotropy at Full Heusler / MgO interfaces

Magnetic tunnel junctions with perpendicular magnetic anisotropy (PMA) have the potential for realizing next generation high density nonvolatile memories and logic devices [1]. The origin of high PMA in these interfaces has been explained by orbital hybridizations at interface along with spin-orbit interactions [2]. Here we present a systematic study of PMA in Heusler alloy [X$_{2}$YZ]/ MgO interfaces using first principle methods with X$=$Co, YZ$=$FeAl, MnGe and MnSi. Among the interfaces studied, we found that Co terminated interface of Co$_{2}$FeAl/MgO gives rise to PMA value of 1.2erg/cm$^{2}$ in agreement with recent experimental observations [3]. On the contrary, FeAl terminated interfaces of the same structure shows in-plane magnetic anisotropy (IMA). We also found that the most of PMA contribution originates from d$_{\mathrm{yz}}$ and d$_{\mathrm{z}}^{2}$ orbitals of Co atoms at the interface. Finally, Co$_{2}$MnGe and Co$_{2}$MnSi structures tend to favor IMA for any termination. \\[4pt] [1] S. Iked et al., Nature materials 9, 721 (2010)\\[0pt] [2] H. X. Yang et al., Physical Review B 84, 054401 (2011).\\[0pt] [3] M. Belmeguenai et al., Cond-mat.mtrl-sci, may 2013, arXiv:1305.0714.