Brillouin scattering determination of magnetic and elastic constants in Invar-type La(FexAl1−x)13 amorphous alloy films

Abstract
Magnetic and elastic constants of Invar‐type La(FexAl1−x)13 amorphous alloy films (x=0.8–0.95) have been determined by Brillouin scattering at 290 K. Observation of the well‐defined standing spin waves up to fourth order allowed us to determine the spin wave stiffness at T/Tc∼0.76, as 63±10 meV A2 for the x=0.8 alloy film. Young’s modulus and Poisson’s ratio as a function of the Fe concentration x have been determined from the surface phase velocities of the Rayleigh and Sezawa waves. Here E(x)=1.08−0.93(1−x)1012 dyn/cm2 for Young’s modulus and σ(x)=0.34±0.2 for Poisson’s ratio have been obtained through numerical analyses for the surface acoustic wave dispersions.