title: Gapless quantum spin liquid ground state in the two-dimensional spin-1/2 triangular antiferromagnet YbMgGaO4.
abstract: Quantum spin liquid (QSL) is a novel state of matter which refuses the conventional spin freezing even at 0 K. Experimentally searching for the structurally perfect candidates is a big challenge in condensed matter physics. Here we report the successful synthesis of a new spin-1/2 triangular antiferromagnet YbMgGaO4 with symmetry. The compound with an ideal two-dimensional and spatial isotropic magnetic triangular-lattice has no site-mixing magnetic defects and no antisymmetric Dzyaloshinsky-Moriya (DM) interactions. No spin freezing down to 60 mK (despite θw ~ -4 K), the power-law temperature dependence of heat capacity and nonzero susceptibility at low temperatures suggest that YbMgGaO4 is a promising gapless (≤|θw|/100) QSL candidate. The residual spin entropy, which is accurately determined with a non-magnetic reference LuMgGaO4, approaches zero (<0.6%). This indicates that the possible QSL ground state (GS) of the frustrated spin system has been experimentally achieved at the lowest measurement temperatures.
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, P. R. China.
authors.forename: Yuesheng
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Liao
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, P. R. China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, P. R. China.
authors.forename: Shiyan
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Jin
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Langsheng
authors.initials: L
authors.lastname: Ling
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Youming
authors.initials: Y
authors.lastname: Zou
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Pi
authors.affiliation: Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Zhaorong
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Wuhan National High Magnetic Field Center, Wuhan 430074, P. R. China.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, P. R. China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, P. R. China.|Department of Physics and Astronomy, Collaborative Innovation Center of Advanced Microstructures, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
authors.forename: Qingming
authors.initials: Q
authors.lastname: Zhang