Interfacial perpendicular magnetic anisotropy and electric field effect in Ta/CoFeB/Mg1−xTixO heterostructures

Abstract

The barrier thickness dependence of perpendicular magnetic anisotropy (PMA) of CoFeB thin films is distinctly different for MgO and Mg0.95Ti0.05O barriers. The electric field effects measured using orthogonal magnetic tunnel junctions show that the coefficient of electric field control of PMA for Ta/CoFeB/Mg0.95Ti0.05O magnetic tunnel junction (MTJ) is around 51 fJ/V m, which is the same order of magnitude as that of Ta/CoFeB/MgO. This indicates that Mg0.95Ti0.05O is a promising barrier material for p-MTJs for voltage controlled magnetic random access memory (MRAM). The perpendicular magnetic anisotropy energy and the electric field effect for the Ta/CoFeB/Mg1−xTixO (x = 0 and 0.05) heterostructures have a strong correlation, suggesting the scalability of voltage controlled MRAM.