Tunable Exciton-Hybridized Magnon Interactions in a Layered Semiconductor

TL;DR

This paper demonstrates tunable exciton-magnon interactions in a layered magnetic semiconductor, showing control via magnetic field orientation and strain, advancing hybrid quantum magnonics.

Contribution

It introduces a method to precisely control exciton-magnon coupling in CrSBr through magnetic field orientation and strain, enabling new quantum magnonic applications.

Findings

Magnetic field direction controls exciton-magnon coupling.

Strain modulates magnon dispersion and induces dark magnon bands.

Achieved unprecedented control of opto-mechanical-magnonic interactions.

Abstract

The interaction between distinct excitations in solids is of both fundamental interest and technological importance. One example of such interactions is coupling between an exciton, a Coulomb bound electron-hole pair, and a magnon, a collective spin excitation. The recent emergence of van der Waals magnetic semiconductors provides a powerful platform for exploring these exciton-magnon interactions and their fundamental properties, such as strong correlation, as well as their photo-spintronic and quantum transduction applications. Here we demonstrate precise control of coherent exciton-magnon interactions in the layered magnetic semiconductor CrSBr. We show that by controlling the direction of applied magnetic fields relative to the crystal axes, and thus the rotational symmetry of the magnetic system, we can tune not only the exciton coupling to the bright magnon, but also to an optically dark mode via magnon hybridization. The exciton-magnon coupling and associated magnon dispersion curves can be further modulated by applying a uniaxial strain. At the critical strain, a dispersionless dark magnon band emerges. Our results demonstrate unprecedented control of the opto-mechanical-magnonic coupling, and a step towards the predictable and controllable implementation of hybrid quantum magnonics.