Intrinsic damping of spin waves by spin current in conducting two-dimensional systems

Abstract

Angle-resolved magneto-Raman scattering has been performed on spin-polarized two-dimensional electron gas embedded in ${\text{Cd}}_{1\ensuremath{-}x}{\text{Mn}}_{x}\text{Te}$ quantum wells to explore the intrinsic damping of propagating spin-wave modes with in plane momentum $q$. The damping rate $\ensuremath{\eta}$ follows a quadratic law $\ensuremath{\eta}={\ensuremath{\eta}}_{0}+{\ensuremath{\eta}}_{2}{q}^{2}$ due to losses in the spin current driven by the magnetization in qualitative agreement with Phys. Rev. B 78, 020404(R) (2008). As a consequence, the propagation length of a spin wave in a conducting system has an intrinsic maximum of importance for spin-wave-based spintronics.