Multiferroics are materials with a coexistence of different types of long-range order. In most cases, a combination of magnetic and ferroelectric order is considered because they offer ways to control magnetism with electric rather than magnetic fields. This could save energy and avoid waste heat because electric fields do not require persistent electrical currents for their generation. Requirements to “good multiferroics” are tough. They are supposed to have a spontaneous magnetization and polarization, preferably parallel to each other, with a strong magnetoelectric coupling between them. Inevitably, this leads to a multiferroic state that is described by a very complex set of order parameters – complex enough to provide the symmetry degrees of freedom to fulfil so many requirements at once. With the focus on electric-field-controlled magnetic order, it may go unnoticed that these degrees of freedom will permit many functionalities other than bulk magnetoelectric coupling. In my talk, I will describe the quest for such functionalities in our group. This includes the inversion of a ferroelectric or a ferromagnetic multi-domain state, condensation of a multiferroic bulk state into a domain wall and – believe it or not – magnetoelectric teleportation.
Department of Materials, ETH Zurich, Switzerland