Magnetoelectric coupling dependent on ferroelectric switching paths in two-dimensional perovskite multiferroics

Two-dimensional (2D) multiferroics have attracted considerable interest since the recent discovery of 2D ferroelectricity and ferromagnetism in van der Waals materials. Here we show the universality of 2D multiferroics in the Ca-based double-perovskite bilayer system and the transition of magnetization that is dependent on the ferroelectric switching paths by combining symmetry analysis and first-principles calculation. We demonstrate that although both the switching of rotation and tilt distortion can lead to polarization reversal, only the latter can cause a change in the direction of magnetization. The breaking of the inversion symmetry correlation between the initial and final polarization states is the key to achieve the transition of magnetization caused by polarization reversal. The ferroelectric switching that reverses tilt distortion via multistep switching generally has the lowest energy barrier, providing the feasibility of controlling magnetization by an electric field.