Spin-ordered ground state and thermodynamic behaviors of the spin-32 kagome Heisenberg antiferromagnet
Tao Liu,¹ Wei Li,^2,3,* and Gang Su^1,†
1Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics,
University of Chinese Academy of Sciences, P.O. Box 4588, Beijing 100049, China
²Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education),
Beihang University, Beijing 100191, China
³International Research Institute of Multidisciplinary Science, Beihang University, Beijing 100191, China
(Received 28 January 2016; revised manuscript received 17 May 2016; published 13 September 2016)

   Three different tensor network (TN) optimization algorithms are employed to accurately determine the ground state and thermodynamic properties of the spin-3/2 kagome Heisenberg antiferromagnet. We found that the √3 ×√3 state (i.e., the state with 120º spin configuration within a unit cell containing 9 sites) is the ground state of this system, and such an ordered state is melted at any finite temperature, thereby clarifying the existing experimental controversies. Three magnetization plateaus (m/ms = 1/3, 23/27, and 25/27) were obtained, where the 1/3-magnetization plateau has been observed experimentally. The absence of a zero-magnetization plateau indicates a gapless spin excitation that is further supported by the thermodynamic asymptotic behaviors of the susceptibility and specific heat. At low temperatures, the specific heat is shown to exhibit a T² behavior, and the susceptibility approaches a finite constant as T → 0. Our TN results of thermodynamic properties are compared with those from high-temperature series expansion. In addition, we disclose a quantum phase transition between q = 0 state (i.e., the state with 120º spin configuration within a unit cell containing three sites) and √3 ×√3 state in a spin-3/2 kagome XXZ model at the critical point c = 0.54. This study provides reliable and useful information for further explorations on high-spin kagome physics.