On the theory of magneto-electric coupling in a ferromagnet/Cr2O3/ferromagnet multilayer

A surface magneto-electric effect in hybrid multilayer systems consisting of antiferromagnet (Cr2O3) and ferromagnet films is considered using the Landau theory. We show that the antiferromagnetic order parameter in Cr2O3 film can be switched without applying an external magnetic field. Only an electric field is needed. The switching happens in the surface region of Cr2O3. The thickness of the switched region is of order of the domain wall width. If the antiferromagnetic layer thinner than the domain wall the electric field switches the whole layer. In the ferromagnet/Cr2O3/ferromagnet structure with the thin antiferromagnetic layer, the magnetoelectric effect can be turned on and off by reversal of magnetization of one of the ferromagnetic leads. The ME effect is "turned on" when the ferromagnetic layers magnetizations are co-directed and "turned off" in the opposite case.