Aharonov-Casher effect and electric field control of magnetization dynamics

A spin wave (SW) propagating in an external electric field acquires an extra phase, the so-called Aharonov-Casher phase. To linear order, that is equivalent the SW frequency shift linear in both the applied electric field and the wave vector of SW's and can be described by adding effective Dzyaloshinskii-Moriya-like interaction between spins. This effect is a promising way to control and manipulate magnetization precession dynamics by electric field and opens up a new way of SWs steering in magnonic devices. The goal of the report is to emphasize a fundamental physical difference in the nature of external electric field effect through the Aharonov-Casher phase shift and of a voltage control of magnetic anisotropy (VCMA). In the context of an experimental performance, we deal with almost identical experimental conditions. Yet, from the quantum physics point of view, we deal with different effects and this is important to understand the experimental results. In the case of the Aharonov-Casher phase shift it is a global nonlocal (topological) effect and in the case of VCMA it is the influence on a system's local (Landau) magnetic parameters (e.g., magnetic anisotropy). © V.N. Krivoruchko, 2020