Controlled refraction and focusing of spin waves determined by the Aharonov-Casher effect

Abstract

The influence of an external static electric field on spin wave (SW) dynamics leads to an additional topological phase called the Aharonov-Casher (AC) phase. It is manifested as a shift in dispersion and the group velocity direction of the spin wave under the electric field. Within a linear approximation, the AC effect can be considered by including the Dzyaloshinskii-Moriya-like interaction between neighboring spins, which is proportional to the applied electric field. In this paper, we use these findings to examine the possibility of the electric field control of the refraction of coherently propagating SWs. This is done by studying the propagation SWs across the boundary between two regions of a homogeneous ferromagnetic film under the influence of different external electric fields. We have derived an analytical expression for a magnetic Snell's law and performed micromagnetic simulations to demonstrate how the AC phase shift can control SW refraction. This effect enables us to quantify the topological AC phase action. It presents a promising approach for guiding and manipulating the phase and energy flow of SWs using an external electric field, opening a way to control magnonic devices. Published by the American Physical Society 2024