Multiferroic properties - structure relationships in epitaxial Bi2FeCrO6 thin films: recent developments

We report recent developments in the growth and characterization of epitaxial Bi2FeCrO6 (BFCO) thin films. The body of experimental data stemming mostly from our investigations, and also considering the few available reports from other groups, allows us to explain the origin(s) of the thickness dependence of the multiferroic properties observed. A drastic reduction of the films' magnetization is observed for film thicknesses larger than 80 nm. This decrease in magnetization is attributed to the formation of defects, such as antisites and antiphase boundaries, in the BFCO films. The change in magnetization is accompanied by a BFCO cell expansion, a consequence of the volume increase of the oxygen octahedra surrounding the Fe cations induced by the defects. BFCO films are ferroelectric for all the thicknesses investigated, ferroelectricity being only moderately affected by the film thickness. (paper)