Epitaxial BiFeO3 multiferroic thin film heterostructures

Abstract

Enhancement of polarization and related properties in heteroepitaxially constrained thin films of the ferroelectromagnet, BiFeO3 is reported. Structure analysis indicates that the crystal structure is monoclinic in contrast to bulk, which is rhombohedral. The films display a room-temperature spontaneous polarization (50-60μC/cm2) almost an order of magnitude higher than that of the bulk (6.1μC/cm2). The observed enhancement is corroborated by first-principles calculations and found to originate from large relative displacements of the Bi, Fe, and O sublattices. The films also exhibit enhanced thickness-dependent magnetism compared with the bulk. These enhanced and combined functional responses in thin film form present an exciting opportunity to create and implement novel thin film devices that actively couple the magnetic and ferroelectric order parameters.