Phonon and magnon dynamics across antiferromagnetic transition in 2D layered van der Waals material CrSBr

• DOI: 10.48550/arxiv.2405.07853
• Publication Date: 2024-05-13
• Authors: E. Uykur; Alexander A. Tsirlin; Fei Long; M. Wenzel; M. Dressel; K. Mosina; Z. Sofer; M. Helm; Shengqiang Zhou
• Keywords: Magnon; Dynamics

We report temperature-dependent reflectivity spectra of the layered van der Waals magnet CrSBr in far-infrared region. Polarization-dependent measurements resolve vibrational modes along E$\|a$- and $b$-axes reveal clear structural anisotropy. While $a$-axis phonons notably harden on cooling, $b$-axis phonon frequencies are almost temperature-independent. A splitting due to antiferromagnetic phase transition is observed for 180~cm$^{-1}$ mode, accompanied by a softening below $T_N$. Furthermore, an additional mode with strong magnetic characteristics at $\sim$360~cm$^{-1}$ identified attributed magnon excitation CrSBr.