Linear magnetoelectricity at room temperature in perovskite artificial superlattices

The primary challenge in the field of multiferroics remains to identify materials that have a functional coupling between an electrical polarization and a magnetization, i.e., a magnetoelectric effect, at room temperature. Such materials may, for example, facilitate technologically important devices based on the electric field control of magnetism. Atomic scale heterostructures of transition metal ABO$_3$ perovskites are an ideal platform to realize designer properties and functionalities that don't exist in the bulk phase diagrams of the constituent materials. Here we take advantage of a recent direction in functional perovskites (where the combination of heterointerfaces with rotations/tilts of the BO$_6$ octahedra facilitate ferroelectric order) to create a new class of room temperature multiferroics in which ferroelectricity induces linear magnetoelectricity. We consider heterostructures of rare-earth orthoferrites of \textit{Pnma} perovskites, (LnFeO$_3$)$_1$/(Ln$^{\prime}$FeO$_3$)$_1$. Computed values of linear ME coefficients are found to be comparable to the prototype ME compound Cr$_2$O$_3$. Finally, we discuss the role of the Ln \textit{f}-states in the ME response.