First-principles investigations of interfacial effect induced by spontaneous polarization of ABO₃ on magnetic anisotropy energy of Fe layer

Lowering the spin-switching energy in spin-based devices is indispensable for their performance enhancement. As a potential way of reducing the spin-switching energy, we explored the effects of ferroelectric (FE) materials on the magnetic properties of ferromagnetic (FM) materials using first-principles density functional theory. We select an iron monolayer as a typical FM material, which is placed on one of various ABO₃ perovskites chosen as prototypical FE materials, where A and B are the alkaline earth (A=Ca, Sr, or Ba) and group 4 transition metal (B=Ti, Zr, or Hf) elements, respectively, and O is oxygen. Then we investigate the correlation between the spontaneous polarization of an ABO₃ perovskite and the magnetic anisotropy energy (MAE) of the Fe monolayer. It is found that the MAE of the iron monolayer is influenced not only by the field effect of FE polarization but also by the structural modification at the interface between FE and FM. Surprisingly, the electric field effect due to polarization is rather insignificant on the MAE causing a small change of up to only a few μ eV. The change in the magnetic moment due to the atomic displacement at the interface has a more correlation with MAE. We also performed machine learning (ML) to describe the universal behavior of FM MAE in the presence of FE. The optimized descriptor obtained by ML indicates that the most relevant features are the magnetic moments of certain atoms at the interface rather than the spontaneous polarization of FE materials as found in our DFT study.