Magnetoelastic coupling and magnetic anisotropy in La0.67Ca0.33MnO3 films

We report the results of magnetization measurements on pseudomorphic (fully strained) c-axis oriented colossal magnetoresistance manganite thin films grown by molecular beam epitaxy. We observe uniaxial magnetic anisotropy (hard axis/easy plane) with the easy plane being the film plane. Within the plane a weaker biaxial anisotropy is observed with [100] (Mn–O bond direction) easy axes. The magnetization dependence of the uniaxial anisotropy constant follows the predicted magnetization dependence of the magnetostriction constants within single-ion models indicating that the anisotropy energy is dominated by strain-induced anisotropy from the lattice constant mismatch with the SrTiO3 substrate. These results indicate a magnetostriction constant λ100≈+7×10−5, and an induced orbital moment of at least 0.02μb/Mn ion. We predict that by appropriate substrate selection an equilibrium out-of-plane magnetization can be produced.