Abstract
We present comprehensive electron spin resonance (ESR) studies of in-plane oriented single crystals of , a quasi-two-dimensional material with honeycomb structure, focusing on its high-field spin dynamics. The measurements were performed in magnetic fields up to 16 T, applied along the [110] and [100] directions. Several ESR modes were detected. Combining our findings with recent inelastic neutron- and Raman-scattering data, we identified most of the observed excitations. Most importantly, we show that the low-temperature ESR response beyond the boundary of the magnetically ordered region is dominated by single- and two-particle processes with magnons as elementary excitations. The peculiarities of the excitation spectrum in the vicinity of the critical field are discussed.
- Received 26 March 2020
- Revised 17 June 2020
- Accepted 19 June 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.037202
© 2020 American Physical Society