Coexistence and Coupling of Spin-Induced Ferroelectricity and Ferromagnetism in Perovskites.

Spin-induced ferroelectricity usually does not occur in perovskites with simple collinear magnetic structures. Here, we demonstrate that in even-layer perovskite systems, some common distortion modes involving octahedral rotation and Jahn-Teller distortion can break the inversion symmetry, allowing the emergence of spin-dependent out-of-plane polarization in a simple magnetic structure. Such spin-induced ferroelectricity is very common in double-perovskite systems and can coexist with ferromagnetism or ferrimagnetism above room temperature. We explain its origin by modifying the spin-dependent p-d hybridization mechanism. Our Letter provides a universal design for two-dimensional multiferroics and enables the control of polarization by means of a magnetic field.