Gapless quantum spin liquid ground state in the two-dimensional spin-1/2 triangular antiferromagnet YbMgGaO4

• Published in: Scientific reports Vol. 5; no. 1; p. 16419
• Main Authors: Li, Yuesheng, Liao, Haijun, Zhang, Zhen, Li, Shiyan, Jin, Feng, Ling, Langsheng, Zhang, Lei, Zou, Youming, Pi, Li, Yang, Zhaorong, Wang, Junfeng, Wu, Zhonghua, Zhang, Qingming
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.11.2015; Nature Publishing Group
• Subjects: 639/301/119; 639/766/119/997; 639/766/119/999; Crystal structure; Entropy; Freezing; Heat; Humanities and Social Sciences; Laboratories; Low temperature; Magnetic fields; multidisciplinary; Physics; Science; Symmetry; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep16419

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 YbMgGaO 4 with sy m metry. 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 θ w  ~ −4 K), the power-law temperature dependence of heat capacity and nonzero susceptibility at low temperatures suggest that YbMgGaO 4 is a promising gapless (≤|θ w |/100) QSL candidate. The residual spin entropy, which is accurately determined with a non-magnetic reference LuMgGaO 4 , 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.