Spin pumping by higher-order dipole-exchange spin-wave modes

Abstract

Spin pumping (SP) and inverse spin Hall effect (ISHE) driven by parametrically-excited dipole-exchange spin waves in a yttrium iron garnet film have been systematically investigated. The measured voltage spectrum exhibits a feature of the field-induced transition from parallel pumping to perpendicular pumping because of the inhomogeneous excitation geometry. Thanks to the high precision of the SP-ISHE detection, two sets of fine structures in the voltage spectrum are observed, which can correspond well to two kinds of critical points in the multimode spin-wave spectrum for magnetic films. One is the q = 0 point of each higher-order dispersion branch, and the other is the local minimum due to the interplay between the dipolar and exchange interactions. These fine structures on the voltage spectrum confirm the spin pumping by higher-order dipole-exchange spin-wave modes, and are helpful for probing the multimode spin-wave spectrum.