Project R-4086

Exploration of single phase layered perovskites as candidate magnetoelectrics (Research)

Magnetoelectric multiferroics show both (ferro)magnetism and ferroelectricity which are strongly coupled, allowing for electric field induced switching of the magnetization. No single phase, room temperature magnetoelectric is currently known, that would allow practical applications based on this phenomenon. Only last year, a new mechanism yielding "hybrid improper ferroelectricity" was theoretically predicted for a layered perovskite Ca3Mn2O7. This mechanism opens a new class of materials, previously not considered as candidates, and may also function at room temperature. The project at hand aims to contribute to an experimental demonstration of the ferroelectric, magnetic and magnetoelectric properties in strained epitaxial thin films of Ca3X2O7 (X=Mn, Ti), and to verify the extension of the proposed mechanism to layered Aurivillius phases and new candidates. Hence it takes up Ghosez and Triscone's suggestion in a recent Nature N&V article [6] where they write "Many efforts are now needed to validate these findings experimentally.' The project goal is highly challenging already concerning materials synthesis, as only high quality samples will be viable for further physical characterization. Chemical solution based routes will be investigated hereto, having the proved advantage of high compositional control and flexibility. Yet, the realization of phase pure epitaxial layers of the envisaged complex oxides would in itself be an achievement beyond current state of the art.

01 October 2012 - 30 September 2014