Distinguishing Backward Volume Magnetostatic Spin Wave Vectors via the Spin Wave Doppler Effect

Abstract

Spin waves (SWs) and their quanta, magnons, are essential to achieving low-power information transmission in future spintronic devices. Backward volume magnetostatic spin waves (BVMSWs) exhibit a unique dispersion relationship: one frequency corresponding to two distinct wave vectors. At low wave numbers, dipole-dipole interactions dominate, resulting in negative group velocities, whereas at high wave numbers, exchange interactions prevail, producing positive group velocities. This dual behavior complicates wave vector identification and obscures intrinsic spin-wave interactions. In this study, we propose an approach based on the spin wave Doppler effect to effectively distinguish different wave vectors. At low wave numbers, the inverse Doppler effect occurs due to antiparallel phase and group velocities, while at high wave numbers, a normal Doppler effect emerges from parallel velocities. This method not only clarifies the underlying spin-wave interactions but also help mitigate serious interference issues in the design of spin logic circuits.