Magnon spin photogalvanic effect induced by Aharonov-Casher phase

TL;DR

This paper introduces the magnon spin photogalvanic effect (SPGE), a novel mechanism allowing electric-field control of magnons via light, leveraging quantum geometric properties for potential applications in spintronics.

Contribution

It proposes the magnon SPGE driven by light, connecting quantum geometry with magnon control, and suggests material candidates for experimental realization.

Findings

Magnon SPGE arises from multiple geometric contributions.

Responses depend on quantum metric and Berry curvature.

Potential for observing topological phase transitions.

Abstract

Magnons are electrically neutral bosonic quasiparticles emerging as collective spin excitations of magnetically ordered materials, and play a central role in the next-generation spintronics owing to its obviating Joule heating. A difficult obstacle for quantum magnonics is that the magnons do not couple to the external electric field directly so that a direct electric manipulation via bias or gate voltage as in conventional charge-based devices seems not applicable. In this work, we propose a new mechanism in which magnons can be excited and controlled by electric field of light directly. Since the electric field of light can be tuned in a wide and easy way, the proposal is of great interest in realistic applications. We call it as the magnon spin photogalvanic effect (SPGE), which comes from five contributions: the Drude, Berry curvature dipole (BCD), injection, shift, and rectification, with distinct geometric origins. We further show that the responses to linearly-polarized or circularly-polarized light are determined by band-resolved quantum metric or Berry curvature, the two combined together just comprise of a quantum geometric tensor. The proposed magnon SPGE can be measured by a characterized topological phase transition. We also discuss a breathing kagome-lattice model of ferromagnets and suggest possible candidate materials to implement it.