Room Temperature Electric-Field Control of Magnetism in Layered Oxides with Cation Order

Searching for materials with room-temperature electric-field control of magnetism has interested researchers for many years with three-dimensional perovskite BiFeO₃-based compounds as the main focus. Here we choose the layered hybrid improper ferroelectric Ruddlesden-Popper oxides as a platform from which to realize electric field controllable magnetism, leveraging a recently identified strain tunable polar-to-nonpolar (P-NP) transition. We first propose a design principle for selecting the required A and B cation chemistries that will ensure (001) A₃B₂O₇ films exhibit P-NP transitions, which we substantiate with density functional calculations. By extending the guideline to B-site ordered A₃BB′O₇ oxides, we identify more compounds exhibiting P-NP transitions marked by the disappearance of an in-plane polarization that can be functionalized. We then demonstrate that weak ferromagnetism can be tuned by an electric field at the boundary of the P-NP transition in B-site ordered (001) A₃BB′O₇ magnetic films, based on which we predict that cation ordered Ca₃TcTiO₇ may be a viable candidate for room-temperature electric-field control of magnetism.