Multiferroic BiFeO3 for conductance control at the LaAlO3/SrTiO3-interface

Multiferroic materials possessing both magnetic and ferroelectric order enable in principle to switch order parameters using not the direct reciprocal field, e.g. to switch the magnetization by an electric field or the electric polarization by a magnetic field. A recent breakthrough was achieved by the demonstration of the ferromagnetic switching of a Co layer with an electric field employing the multiferroic BiFeO₃. The latter material is a perovskite based oxide that shows stable ferro-electricity as well as an antiferromagnetic order at room temperature. Due to a Dzyaloshinskii-Moriya interaction induced by rotation of oxygen octahedra leading to noncollinear Fe-O-Fe bonds a small canted ferromagnetic moment exists that can couple to a neighboring ferromagnetic layer. In addition exchange bias effects can occur in such a configuration.