Structural and magnetic properties of La0.7Sr0.3MnO3 thin films integrated onto Si(100) substrates with SrTiO3 as buffer layer

Abstract

La0.7Sr0.3MnO3 (LSMO) thin films with a thickness d of 10, 20, 60, and 100 nm were grown on 20-nm-thick SrTiO3-buffered (100) silicon substrates by a reactive molecular beam epitaxy. For all samples, x-ray diffraction (XRD) revealed an excellent epitaxy with in-plane cubic [100] and [010] axes of LSMO. The XRD measured values of the out-of-plane lattice parameter suggest that the strain state does not vary significantly from sample to sample. A super conducting quantum interference device reveals that the room temperature magnetization at saturation increases with d and nearly reaches the bulk value for d = 100 nm; the Curie temperature ranges in the 320–350 K interval, to compare to 360 K in the bulk. Ferromagnetic resonance (FMR) in cavity (at 9.5 GHz) and microstrip FMR used to investigate the dynamic magnetic properties, revealed a fourfold anisotropy showing its easy axes along the [110] and [11¯0] directions. In the thickest samples (d > 20 nm), the FMR spectra present two distinct resonant modes. This splitting is presumably due to the simultaneous presence of two different magnetic phases.