Ferroelectric control of magnetic anisotropy in multiferroic heterostructure EuSn2As2/In2Se3

The electrically nonvolatile control of the easy magnetization axis (EMA) in two-dimensional ferromagnets has attracted significant attention due to its promising applications in spintronic devices. Multiferroic heterostructures, consisting of vertically stacked ferromagnetic and ferroelectric monolayers, have been proposed to manipulate the EMA by reversing the ferroelectric polarization. Here, based on first-principles calculations, we predict a strong magnetoelectric coupling in the multiferroic heterostructure ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}/{\mathrm{In}}_{2}{\mathrm{Se}}_{3}$. Specifically, the EMA of the ferromagnetic monolayer ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$, characterized by a high spin magnetic moment of the rare-earth element Eu, can be switched between in-plane and out-of-plane directions by reversing the polarization direction of the ferroelectric monolayer ${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$. Our analysis reveals that the polarization direction significantly influences the charge transfer at the interface, introducing band bending, modifying the electronic structure, and resulting in a significantly large difference in the magnetic anisotropy associated with the spin-orbit coupling (SOC) of the Eu $4f$, Sn $4p$, and As $4p$ orbitals. Furthermore, the shape magnetic anisotropy arising from dipole-dipole interactions is significant due to high spin magnetic moments. Thus, the combined effects of SOC and shape magnetic anisotropies determine the switching of EMA. Our findings present an opportunity to achieve nonvolatile electrical control of magnetic anisotropy in multiferroic heterostructures with coupled ferroelectric and ferromagnetic orders.