Study of the intensity asymmetry in Brillouin light scattering from magnons in FeNi thin films

摘要

The Stokes-anti-Stokes intensity asymmetry, observed by Brillouin light scattering from surface magnetic excitations in thin FeNi films, has been studied by replacing substrates with different dielectric constant as well as varying the applied magnetic field and the laser incident angle. The experimental results show that the Stokes-anti-Stokes intensity ratio depends upon the applied magnetic fields, the wave vectors and also the material of the substrates used to support the FeNi films. Most interesting is that for a fixed magnetic field and a fixed wave vector, the intensity ratio is much more significant for the FeNi film deposited on Nb-doped SrTiO_3 substrate than that deposited on surface oxidized Si substrate. The phenomenon of the different asymmetry is depending on the dielectric constant of the substrates. The tendency is in agreement with the theory.