Neutron studies of functional multiferroic BiFeO3 thin films

Abstract

In a multiferroic material, ferromagnetism (FM) and ferroelectricity (FE) coexist, presenting exciting opportunities for research into new phenomena and technological innovation. Bismuth Ferrite (BiFeO3) is among the rare cases where both properties exist at room temperature [1]. As such, its use in functional thin film heterostructures, like multiferroic tunnel junctions or exchange bias systems, which combine multiferroic (MF) and ferromagnetic layers, such as La0.67Sr0.33MnO3 (LaSrMnO3), is of particular interest [2]. In a series of resistivity based measurements [3] and neutron diffraction and polarised neutron reflectometry measurements of BiFeO3/LaSrMnO3 thin film bilayers we have investigated and found evidence of electromagnetic coupling between the layers. We use these results to provide deeper insight into the complex interplay between the orbital and spin degrees of freedom at the bilayer interface. Neutron experiments were performed at the Bragg Institute, ANSTO in Sydney, Australia, FRM-II in Munich, Germany and NRC-CNBC in Chalk River, Canada.