Magnetoelectric Phase Control at Domain-Wall-Like Epitaxial Oxide Multilayers

Ferroelectric domain walls are nanoscale objects that can be created, positioned, and erased on demand. They often embody functional properties that are distinct from the surrounding bulk material. Enhanced conductivity, for instance, is observed at charged ferroelectric domain walls. Regrettably, domain walls of this type are scarce because of the energetically unfavorable electrostatics. This hinders the current technological development of domain-wall nanoelectronics. Here this constraint is overcome by creating robust domain-wall-like objects in epitaxial oxide heterostructures. Charged head-to-head (HH) and tail-to-tail (TT) junctions are designed with two ferroelectric layers (BaTiO3 and BiFeO3) that have opposing out-of-plane polarization. To test domain-wall-like functionalities, an ultrathin ferromagnetic La0.7Sr0.3MnO3 layer is inserted into the junctions. The interfacial electron or hole accumulation at the interfaces, set by the HH and TT polarization configurations, respectively, controls the LSMO conductivity and magnetization. Thus it is proposed that trilayers reminiscent of artificial domain walls provide magnetoelectric functionality and may constitute an important building block in the design of oxide-based electronic devices.