Phonon Emission from Terbium Films at 15 GHz

Abstract
Using a tunable phonon spectrometer, we have observed phonon emission from films of terbium at 1.6°K. The phonon frequency, 15.15 GHz, was found to be the same as the frequency of an rf magnetic field applied parallel to the surface of the film. This observation provides direct support for the so-called free-lattice model of dynamic magneto-elastic coupling in rare-earth metals.