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arXiv · 2107.11942

Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu$_3$(OH)$_6$Br$_2$[Br$_{x}$(OH)$_{1-x}$]

Zhenyuan Zeng·Xiaoyan Ma·Si Wu·Hai-Feng Li·Zhen Tao·Xingye Lu·Xiao-hui Chen·Jin-Xiao Mi·Shi-Jie Song·Guang-Han Cao·Guangwei Che·Kuo Li·Gang Li·Huiqian Luo·Zi Yang Meng·Shiliang Li
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Abstract

We studied the magnetic properties of YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(OH)$_{x}$] ($x$ = 0.33), where Cu$^{2+}$ 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 $T^2$ 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 YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(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.

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Zhenyuan Zeng, Xiaoyan Ma, Si Wu, Hai-Feng Li, Zhen Tao, Xingye Lu, Xiao-hui Chen, Jin-Xiao Mi, Shi-Jie Song, Guang-Han Cao, Guangwei Che, Kuo Li, Gang Li, Huiqian Luo, Zi Yang Meng, Shiliang Li. 2022-03-16. Possible Dirac quantum spin liquid in a kagome quantum antiferromagnet YCu$_3$(OH)$_6$Br$_2$[Br$_{x}$(OH)$_{1-x}$]. https://doi.org/10.1103/physrevb.105.l121109

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