Abstract
We present high-field electron spin resonance (ESR) studies of the honeycomb-lattice material , a prime candidate to exhibit Kitaev physics. Two modes of antiferromagnetic resonance were detected in the zigzag ordered phase, with magnetic field applied in the plane. A very rich excitation spectrum was observed in the field-induced quantum paramagnetic phase. The obtained data are compared with the results of recent numerical calculations, strongly suggesting a very unconventional multiparticle character of the spin dynamics in . The frequency-field diagram of the lowest-energy ESR mode is found consistent with the behavior of the field-induced energy gap, revealed by thermodynamic measurements.
- Received 22 June 2017
- Revised 29 November 2017
DOI:https://doi.org/10.1103/PhysRevB.96.241107
©2017 American Physical Society