MAGNETOELASTIC DISSIPATION IN MACROSCOPIC MAGNETIZATION TUNNELING

The tunneling of the total magnetization of a small (approximately 100 angstrom) magnetic particle out of a metastable easy direction is a promising candidate for macroscopic quantum tunneling. It is shown that the coupling of the magnetization to the phonons is an extremely weak source of dissipation that does not reduce the tunneling rate. A model in which the magnetic particle is embedded in a solid medium is considered, and the spectral density is derived for various crystal symmetries.