Actuation, propagation, and detection of transverse magnetoelastic waves in ferromagnets

TL;DR

This paper investigates how ultrasonic waves propagate in ferromagnets, focusing on boundary conditions, energy transport, and magnetoelastic coupling, revealing resonant effects and mechanisms for exciting magnetization dynamics.

Contribution

It introduces a scattering framework for energy transport in ferromagnets and uncovers resonant magnetoelastic effects near the dispersion anti-crossing point.

Findings

Magnetoelastic coupling causes non-zero magnetic and elastic energy exchange.

Resonant enhancement occurs near the dispersion relation anti-crossing.

Acoustic waves can excite magnetization dynamics around ferromagnetic resonance.

Abstract

We study propagation of ultrasonic waves through a ferromagnetic medium with special attention to the boundary conditions at the interface with an ultrasonic actuator. In analogy to charge and spin transport in conductors, we formulate the energy transport through the system as a scattering problem. We find that the magneto-elastic coupling leads to a non-vanishing magnetic (elastic) energy accompanying the acoustic (spin) waves with a resonantly enhanced effect around the dispersion relation anti-crossing point. We demonstrate the physics of excitation of magnetization dynamics via acoustic waves injection around the ferromagnetic resonance frequency.