Quantum spin liquids (QSLs) are topologically ordered exotic states of matter that host fractionalized excitations. Kitaev proposed a particular route towards a QSL via strongly bond-dependent interactions on the hexagonal lattice. A number of candidate Kitaev QSL materials have been pursued, but all have appreciable non-Kitaev interactions, which put these systems far from the QSL regime. Using time-domain terahertz spectroscopy (TDTS) we observed a broad magnetic continuum over a wide range of temperature and field in the honeycomb cobalt-based magnet, BaCo2(AsO4)2, which has been proposed to be more ideal versions of a Kitaev QSL. Applying a small in-plane magnetic field of ∼ 0.5 T suppresses the magnetic order and at at even higher fields gives rise to a spin-polarized state. With 4T magnetic field oriented principally out-of-plane, a broad magnetic continuum was observed that could be consistent with a field induced QSL. Our results indicate BaCo2(AsO4)2 to be a promising QSL candidate.
@article{arxiv.2106.13418,
title = {A magnetic continuum observed by terahertz spectroscopy in a quantum spin liquid candidate BaCo$_2$(AsO$_4$)$_2$},
author = {Xinshu Zhang and Yuanyuan Xu and T. Halloran and Ruidan Zhong and R. J. Cava and C. Broholm and N. Drichko and N. P. Armitage},
journal= {arXiv preprint arXiv:2106.13418},
year = {2022}
}