Multiferroic (MF) materials with simultaneous ferroelectricity and magnetism hold great potential for novel technological applications such as multistate memory devices with fast, low-power heterogeneous read/write capabilities. However, it remains a big challenge to find proper single-phase materials with significant magnetoelectric coupling at room temperature.

So far BiFeO3 is the best known single phase room temperature MF material, but the problem is its second phase, high conductivity and antiferromagnetism, which strongly suppress the ferroelectric response and result in the low preformance of its written/read operations. Dr Yan at QMUL has eighteen years research experience on lead-free Aurivillius phase ferroelectric materials.  Recently he successfully replaced some B-sites cations in Aurivillius materials with magnetic atoms to produce multiferroicity. The materials were found to possess weak room temperature ferromagnetism and are single phase according to XRD, neutron diffraction and SEM/EDX results. Prof Jia’s expertise in magnetoelectric (ME) effects has given a big push to the experimental development of ME hexaferrites. Our joint research on MF materials is believed not only to develop a deep understand of the underlying physics of MF behaviours in Aurivillius-based materials but also to provide a pathway to achieving strong ME effects for more energy efficient spintronic devices at room temperature. Particularly, in this project, our aims are to:

1, Clarify that the origin of the ferromagnetic behaviour is from a main phase or structurally undetectable minor magnetic second phase;

2, Prepare textured single crystal materials to optimise ferroelectric, ferromagnetic and more important MF properties;

3, Model and characterise the relationship between ferroelectric and ferromagnetic domains (and domain walls) in a single grain.