We report the first observation of standing spin-wave modes by means of Brillouin light scattering in thin sputtered films of amorphous metallic ${\mathrm{Fe}}_{80}$${\mathrm{B}}_{20}$. Results agree with a classical theory and permit determination of spin-wave stiffness $D=(1.4\mathrm{}\pm 0.2)\times {10}^{-9\mathrm{}}$ Oe ${\mathrm{cm}}^2$. The value of $D$ is twice as large as that obtained from low-temperature magnetization measurements.

• Received 20 December 1978

DOI:https://doi.org/10.1103/PhysRevLett.43.711