First-principles study on the magnetic anisotropy of the CoFe/ MgAl2O4 heterostructures

Abstract

Practical applications of novel spintronic devices require heterostructures with high magnetic anisotropy (MA). Here, the MA of the CoFe/MgAl2O4 heterostructures was studied by using first-principles calculations. It was found that all the CoFe/MgAl2O4 models exhibit perpendicular magnetic anisotropy (PMA) and that the Co/MgAl2O4 interface is generally more favorable than the Fe/MgAl2O4 interface for inducing large PMA. Importantly, the CoFe/MgAl2O4 heterostructure with the Co/MgAl2O4 interface shows an interfacial PMA density of up to ∼ 0.91 mJ/m2. Moreover, the PMA of the CoFe/MgAl2O4 heterostructure is greatly enhanced compared to the corresponding bare CoFe film. Through density of state analysis combined with the layer- and orbital-hybridization-resolved MA contributions, it is found that the positive contribution from spin-orbit coupling interaction between opposite spin dz2 and dyz orbitals of the interfacial Co for CoFe/MgAl2O4 heterostructure is significantly higher than that of the surface Co for the bare CoFe film, which can well explain the enhancement of the PMA. Our calculated results extend the application of perpendicular magnetic tunnel junctions based on MgAl2O4.