We present direct evidence for room-temperature magnetization reversal induced by an electric field in epitaxial ferroelectric BiFeO3-ferrimagnetic CoFe2O4 columnar nanostructures. Piezoelectric force microscopy and magnetic force microscopy were used to locally image the coupled piezoelectric-magnetic switching. Quantitative analyses give a perpendicular magnetoelectric susceptibility of approximately 1.0 x 10(-2) G cm/V. The observed effect is due to the strong elastic coupling between the two ferric constituents as the result of the three-dimensional heteroepitaxy.

We show the importance of the role of strain in La0.7Sr0.3MnO3 films by revealing the dominance of stress anisotropy effects over magnetocrystalline anisotropy effects in the magnetic anisotropy of these films. Magnetic anisotropy measurements of (001) and (110) La0.7Sr0.3MnO3 thin films on SrTiO3 and LaGaO3 substrates, with excellent structural quality, reveal twofold symmetry on (110) La0.7Sr0.3MnO3 films and fourfold symmetry on (001) films. Such symmetries can only be explained by stress anisotropy contributions in the plane of the film. In conjunction with the thickness dependence of the magnetic properties, the results indicate the dominant role of strain in the magnetic properties of these doped manganites.

No abstract