Temperature dependence of magnetic properties of La0.7Sr0.3MnO3/SrTiO3 thin films on silicon substrates

International audience20-nm-thick and 50-nm-thick La0.7Sr0.3MnO3 films were grown by molecular-beam epitaxy on Si 001 substrates overlaid by a 20-nm-thick SrTiO3 001 buffer layer. X-ray diffraction and atomic force microscopy studies demonstrate their epitaxial 001 orientation. Their static magnetic properties are investigated as a function of the temperature using a superconducting quantum interference device. Ferromagnetic resonance FMR inside a cavity and microstrip ferromagnetic resonance MS-FMR are used to study their dynamic properties. The field dependence of the MS-FMR resonance frequency as a function of a perpendicular applied field provides a precise evaluation of the g factor and of the effective demagnetizing field 4 Mef f at room temperature. The perpendicular uniaxial and the in-plane anisotropies strongly decrease versus temperature. The excellent epitaxial crystallographic orientation due to the SrTiO3 buffer gives rise to an observed fourfold symmetry of the in-plane anisotropy which is assumed of magnetocrystalline nature. The large perpendicular uniaxial anisotropy gives rise to an effective demagnetizing field significantly larger than the resulting one from the sole contribution of the saturation magnetization. It is most probably induced by the interfacial strain