Ferromagnetic resonance and Brillouin light scattering from epitaxial FexSi1−x films on Si(111) (abstract)

Abstract

The magnetic properties of epitaxial FexSi1−x films on Si(111) have been determined by means of ferromagnetic resonance (FMR) and Brillouin light scattering (BLS). The investigated films are (111) oriented, with thicknesses h=150 Å, 250 Å, 710 Å, and Fe concentrations x=0.75, 0.79, and 0.75, respectively. All experiments have been carried out at room temperature. For BLS, the frequencies of both surface and bulk magnons have been measured as a function of the external in plane field H and the in plane direction of magnon propagation versus the main crystallographic axis. Moreover, the wave vector dependence has been used to identify the surface and bulk magnons present in the thicker films. FMR has been used in the parallel configuration (PC) and normal configuration (NC), where the external applied field lies in the sample plane and normal to the sample, respectively. Several waveguide setups were used to cover the frequency range from 18 to 92 GHz. For the numerical analysis we used the resonance conditions for a thin single crystalline film grown in the (111) plane. From our fits we obtained for the Landé g value 2.1, for the saturation induction 4πMs=8.8 kG, 10.7 kG, 13.7 kG for h=150 Å, 710 Å, and 250 Å, respectively. The magnetic parameters have been found to depend strongly on the Fe concentrations and FexSi1−x-Si substrate interface interdiffusion. The magnetic parameters of epitaxial FexSi1−x films are in agreement with the data obtained from single crystals by Hines et al. The Landau–Lifshitz FMR relaxation constant is very small, ranging from 5 to 8×107 rad/s.