Ferromagnetism and ferroelectricity in epitaxial BiMnO{sub 3} ultra-thin films

We studied the ferroelectric and ferromagnetic properties of compressive strained and unstrained BiMnO{sub 3} thin films grown by rf-magnetron sputtering. BiMnO{sub 3} samples exhibit a two-dimensional cube-on-cube growth mode and a pseudo-cubic structure up to a thickness of 15 nm and of 25 nm when deposited on (001) SrTiO{sub 3} and (110) DyScO{sub 3}, respectively. Above these thicknesses, we observe a switching to a three-dimensional island growth mode and a simultaneous structural change to a (00l) oriented monoclinic unit cell. While ferromagnetism is observed below a T{sub C} ≈ 100 K for all samples, signatures of room temperature ferroelectricity were found only in the pseudo-cubic ultra-thin films, indicating a correlation between electronic and structural orders.