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The ferroelectric switching effect on perpendicular magnetic anisotropy is examined for the case of the BaTiO3/L10-CoFe interface through first-principles calculations of film magnetocrystalline anisotropy energy (MAE), both with the frozen-potential method and the second-order perturbation theory. The ferroelectric switching-MAE relationship is shown to have opposite trends for BaO- and TiO2-terminated interfaces because of the distinct orbital interaction mechanisms predominant in each termination configuration. The ferroelectric switching effect, changes in Fe-O bond lengths, and termination constitute three different contributors to MAE change, each with a different penetration depth into the CoFe film. The top surface CoFe atoms are shown to feature a high density of minority-spin 3dxz states, which could play a role in influencing the ferroelectric switching-MAE relationship in cases where the top surface undergoes modifications.

Electric-field control of magnetocrystalline anisotropy energy (MAE) is important for the optimal performance of the tunnel junction components of the STT-MRAM. In such a device, a high MAE of the free magnetic layer improves storage robustness, whereas a low MAE is also useful to keep energy expenditure in the switching process at a minimum. Using the frozen potential method to calculate the MAE of the CoFe layer, the electric-field control of MAE in the BaTiO3/CoFe/(Hf, Ta, W, Re, Os, Ir, Pt, or Au) heterostructure is studied. Electric field tuning of MAE is determined to be possible through switching the direction of BaTiO3 ferroelectric polarization, although both the tuning effect and the MAE depend strongly on the choice of the 5d transition metal element in the capping layer. The results predict a complicated behavior of both MAE and the underlayer polarization effect as we progress down the 5d series of elements as the choice of the capping layer element. Using the second-order perturbation theoretical framework, this behavior can nevertheless be explained by mechanisms including CoFe/capping layer interface hybridization and 5d band-filling trends in the capping layer.