Strong Exciton-Phonon Coupling as a Fingerprint of Magnetic Ordering in van der Waals Layered CrSBr

TL;DR

This study reveals strong exciton-phonon coupling in the layered magnetic semiconductor CrSBr, linking optical, electronic, and magnetic properties, with implications for controlling light-matter interactions in magnetic 2D materials.

Contribution

It demonstrates the effective exciton-phonon coupling in CrSBr and identifies the specific phonon mode involved, providing new insights into exciton dynamics in magnetic layered materials.

Findings

Identification of exciton-phonon coupling at 118 cm-1

Support for magnetic and optical property interaction

Implications for light-matter control in magnetic semiconductors

Abstract

The layered, air-stable van der Waals antiferromagnetic compound CrSBr exhibits pronounced coupling between its optical, electronic, and magnetic properties. As an example, exciton dynamics can be significantly influenced by lattice vibrations through exciton-phonon coupling. Using low-temperature photoluminescence spectroscopy, we demonstrate the effective coupling between excitons and phonons in nanometer-thick CrSBr. By careful analysis, we identify that the satellite peaks predominantly arise from the interaction between the exciton and an optical phonon with a frequency of 118 cm-1 (~14.6 meV) due to the out-of-plane vibration of Br atoms. Power-dependent and temperature-dependent photoluminescence measurements support exciton-phonon coupling and indicate a coupling between magnetic and optical properties, suggesting the possibility of carrier localization in the material. The presence of strong coupling between the exciton and the lattice may have important implications for the design of light-matter interactions in magnetic semiconductors and provides new insights into the exciton dynamics in CrSBr. This highlights the potential for exploiting exciton-phonon coupling to control the optical properties of layered antiferromagnetic materials.