Nucleation-induced self-assembly of multiferroic BiFeO3-CoFe2O4 nanocomposites.

Large areas of perfectly ordered magnetic CoFe2O4 nanopillars embedded in a ferroelectric BiFeO3 matrix were successfully fabricated via a novel nucleation-induced self-assembly process. The nucleation centers of the magnetic pillars are induced before the growth of the composite structure using anodic aluminum oxide (AAO) and lithography-defined gold membranes as hard mask. High structural quality and good functional properties were obtained. Magneto-capacitance data revealed extremely low losses and magneto-electric coupling of about 0.9 µC/cmOe. The present fabrication process might be relevant for inducing ordering in systems based on phase separation, as the nucleation and growth is a rather general feature of these systems.