1Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190 3State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433 4Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USA 5Institute for Advanced Study, Tsinghua University, Beijing 100084 6Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 7Collaborative Innovation Center of Quantum Matter, Beijing 100190 8Department of Physics, Okayama University, Okayama 700-8530, Japan 9Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055 10Beijing Computational Science Research Center, Beijing 100193
Abstract：We report a new kagome quantum spin liquid candidate Cu$_3$Zn(OH)$_6$FBr, which does not experience any phase transition down to 50 mK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature ($\sim$200 K). A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from $^{19}$F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin-1/2 spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fractionalization in the fractional quantum Hall state.
Wen X 2004 Quantum Field Theory of Many-Body Systems:From the Origin of Sound to an Origin of Light and Electrons Oxford Graduate Texts (OUP Oxford, 2004)
Helton J S, Matan K, Shores M P, Nytko E A, Bartlett B M, Yoshida Y, Takano Y, Suslov A, Qiu Y, Chung H, Nocera D G and Lee Y S 2007 Phys. Rev. Lett.98 107204
[18]
Mendels P, Bert F, M A de Vries, Olariu A, Harrison A, Duc F, Trombe J C, Lord J S, Amato A and Baines C 2007 Phys. Rev. Lett.98 077204
[19]
Zorko A, Nellutla S, J van Tol, Brunel L C, Bert F, Duc F, Trombe C, M A de Vries, Harrison A and Mendels P 2008 Phys. Rev. Lett.101 026405
2017, Vol. 34 
