We studied the magnetic properties of YCu3(OH)6Br2[Br1−x(OH)x] (x = 0.33), where Cu2+ ions form two-dimensional kagome layers. There is no magnetic order down to 50 mK while the Curie-Weiss temperature is on the order of -100 K. At zero magnetic field, the low-temperature specific heat shows a T2 dependence. Above 2 T, a linear temperature dependence term in specific heat emerges, and the value of γ=C/T increases linearly with the field. Furthermore, the magnetic susceptibility tends to a constant value at T=0. Our results suggest that the magnetic ground state of YCu3(OH)6Br2[Br1−x(OH)x] is consistent with a Dirac quantum-spin-liquid state with a linearly dispersing spinon strongly coupled to an emergent gauge field, which has long been theoretically proposed as a candidate ground state in the two-dimensional kagome Heisenberg antiferromagnetic system.
@article{arxiv.2107.11942,
title = {Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu$_3$(OH)$_6$Br$_2$[Br$_{x}$(OH)$_{1-x}$]},
author = {Zhenyuan Zeng and Xiaoyan Ma and Si Wu and Hai-Feng Li and Zhen Tao and Xingye Lu and Xiao-hui Chen and Jin-Xiao Mi and Shi-Jie Song and Guang-Han Cao and Guangwei Che and Kuo Li and Gang Li and Huiqian Luo and Zi Yang Meng and Shiliang Li},
journal= {arXiv preprint arXiv:2107.11942},
year = {2022}
}