Current-induced spin-wave Doppler shift and attenuation in compensated ferrimagnets

We theoretically and numerically study current-induced modification of ferrimagnetic spin-wave dynamics when an electrical current generates adiabatic and nonadiabatic spin-transfer torques. We find that the sign of the Doppler shift depends on the spin-wave handedness because the sign of spin polarization carried by spin waves depends on the spin-wave handedness. It also depends on the sign of the adiabatic-torque coefficient, originating from unequal contributions from two sublattices. For a positive nonadiabaticity of spin current, the attenuation lengths of both right- and left-handed spin waves increase when electrons move in the same direction with spin-wave propagation. Our result establishes a way to simultaneously measure important material parameters of a ferrimagnet, such as angular momentum compensation point, spin polarization, and nonadiabaticity using current-induced control of ferrimagnetic spin-wave dynamics.

Automated summary

The study investigates the modification of ferrimagnetic spin-wave dynamics induced by electrical current, showing that the sign of the Doppler shift is influenced by the handedness of spin waves. When electrons move in the same direction as spin-wave propagation, the attenuation lengths of both right- and left-handed spin waves increase.