Coherent magnon-exciton coupling in magnetic semiconductors*

Two-dimensional (2D) magnetic semiconductors possess tightly bound excitons with large oscillator strength and long-lived coherent magnons due to the presence of bandgap and spatial confinement. While magnons and excitons are energetically mismatched by orders of magnitude, their coupling can lead to efficient optical access to spin information. The ability to overcome energy mismatch between magnon and exciton combined with optical excitation and detection renders 2D magnetic semiconductors attractive candidates for quantum transducers. In this presentation, I will discuss strong magneto-electronic and magnetoelastic coupling and implications of these couplings in the 2D van der Waals antiferromagnetic semiconductor, CrSBr. Because of both magnetic and semiconducting properties in CrSBr, excitons are highly sensitive to spin environments. Optical excitation of coherent spin waves can dynamically modulate the dielectric environment and excitons can sensitively detect these changes. I will also discuss strong magnetoelastic coupling in CrSBr that induces transient strain fields to selectively launch a narrow range of wavevector and frequency of both coherent magnons and acoustic phonons.