Spin–phonon coupling and phonon dynamics in van der Waals antiferromagnetic CrSBr

Abstract

As a vander Waals antiferromagnetic semiconductor, CrSBr exhibits unique anisotropy and hosts various physical phenomena (e.g., magnons, phonons, excitons, and polarons), showing great application potential. However, extensive investigations of its spin–phonon coupling and phonon dynamics are still limited. In this study, we employed a combination of group theory analysis and first-principles calculations and carried out comprehensive angle-resolved polarization-dependent and temperature-dependent Raman spectroscopy measurements on CrSBr single crystals. The abnormal shifts in phonon frequency and linewidth were observed below the Néel temperature, and the underlying spin–phonon coupling within CrSBr was unveiled. Additionally, phonon softening with increasing temperature was indicated by Raman spectroscopy, mainly due to phonon anharmonicity. Phonon scattering rates also increased with temperature due to enhanced phonon–phonon interactions, supporting the prediction of low thermal conductivity in CrSBr. The anisotropic structure of CrSBr, combined with spin–phonon coupling effects and phonon anharmonicity, holds significant potential for spintronics and thermoelectric applications.