Ultrasonic Attenuation in the Helical Spin State of the Rare-Earth Metals

Abstract

Theory and experiment are presented for the ultrasonic attenuation of the rare-earth metals. In the helical spin state of the metals, the sound energy transferred to the spin system is dissipated to the lattice by the spin rotation around the $c$ axis, arising from the spin-lattice relaxation mechanism, which may explain the large increases of the attenuation observed on Dy and Ho single crystals below their Néel temperatures.