Exciton-magnon splitting in van der Waals antiferromagnet MnPS$_3$ unveiled by second-harmonic generation

TL;DR

This study uses second-harmonic generation spectroscopy to observe exciton-magnon interactions in the 2D antiferromagnet MnPS3, revealing exciton-induced magnon splitting and magnetoelectric effects, advancing understanding of quasiparticle interactions in 2D magnetic materials.

Contribution

First demonstration of exciton-magnon splitting in a van der Waals antiferromagnet using nonlinear optical spectroscopy, highlighting strong exciton-magnon coupling in 2D magnets.

Findings

Observation of two exciton-magnon peaks in MnPS3

Detection of exciton-induced magnon density of states splitting

Large linear magnetoelectric effect of excitons

Abstract

Ultrafast and coherent generation of magnons is of great significance for high-speed antiferromagnetic spintronics. One possible route is by exciton-magnon pairwise optical excitation. To date, such exciton-magnon transitions have been studied mostly by linear optical means in a limited number of conventional three-dimensional antiferromagnets. Here we investigate this correlated transition in van der Waals antiferromagnet MnPS$_3$ by using resonant second-harmonic generation spectroscopy, a nonlinear optical probe sensitive to the symmetry of electronic and magnetic excitations. Two exciton-magnon peaks are observed, in line with the exciton-induced splitting of magnon density of states predicted by a Koster-Slater type theory, indicating significant exciton-magnon interactions. In addition, a large linear magnetoelectric effect of excitons is observed. These findings provide renewed understandings on the correlation effects in two-dimensional magnets with enhanced quasiparticle scattering cross-sections, and point to potential coherent control among charge, spin and orbital degrees of freedom in two-dimensional magnets by optical means.