Emergent Magnetism in Ferroelectric Thin Films

Reports on conductivity, superconductivity and magnetism at atomically precise interfaces between non-magnetic insulating oxides have sparked intense research on emergent phenomena. We have recently demonstrated robust high-temperature magnetism in perovskite oxide ferroelectric films sandwiched between an insulator and a metal. Our macroscopic results and model calculations suggest that the observed magnetic response is due to the accumulation of screening charges within the ferroelectric film. A verification is vital to solidly prove that magnetisation does exist, the magnetic layer is indeed located inside the ferroelectric film, and the magnetisation is independent of the chemical composition of the materials used. A key requirement is the determination of the magnetisation depth profile in the heterostructure. Polarised neutron reflectometry constitutes the ideal technique for this.