BRILLOUIN-SCATTERING DETERMINATION OF MAGNETIC AND ELASTIC-CONSTANTS IN INVAR-TYPE LA(FEXAL1-X)(13) AMORPHOUS ALLOY-FILMS

Magnetic and elastic constants of Invar-type La(Fe(x)Al1-x)(13) amorph ous alloy films (x=0.8-0.95) have been determined by Brillouin scatter ing at 290 K. Observation of the well-defined standing spin waves up t o fourth order allowed us to determine the spin wave stiffness at T/T- c similar to 0.76, as 63+/-10 meV A(2) 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 Rayleig h and Sezawa waves. Here E(x)=1.08-0.93(1-x)10(12) dyn/cm(2) for Young 's modulus and sigma(x)=0.34+/-0.2 for Poisson's ratio have been obtai ned through numerical analyses for the surface acoustic wave dispersio ns.