Title: Characterizing Random-singlet State in Two-dimensional Frustrated Quantum Magnets and Implications for the Double Perovskite Sr2CuTe1-xWxO6
Speaker: Shou-Shu Gong, Department of Physics, Beihang University
Time: 9:30 am, Wednesday, Mar. 18, 2020 (UTC/GMT+08:00)
Online venue: Zoom online meeting ID: 987 575 796
Abstract: Motivated by the spin-liquid-like compound double perovskite Sr2CuTe1−xWxO6 , which realizes the simultaneous tuning of frustration and disorder, we study the spin-1/2 Heisenberg model with the random nearest- neighbor (J1) and next-nearest-neighbor (J2) interactions on the square lattice. By using the large-scale density matrix renormalization group (DMRG) calculation on the cylinder systems with circumference up to 10, we identify a magnetic disorder phase between the Neel and the stripe magnetic phase with growing J2/J1. In this disorder phase, the spin-freezing order parameter follows the same system length dependence as that in the one-dimensional random singlet (RS) state and is extrapolated to vanishing in the thermodynamic limit, which indicates the absent spin-glass order. On the large-size system, we unveil the power-law decay of the mean spin correlations as r-2 as a function of distance r. We propose this disorder state as a two-dimensional analog of the RS state in one dimension. The analysis of the different clusters in this RS state demonstrates the formed orphan spins, which may account for the gapless excitations. Our results indicate that this RS state may belong to the same ﬁxed point as the RS state recently found in the designed random J−Q model, and the large-scale DMRG simulation opens new opportunities for further studies on the spin-liquid-like frustrated antiferromagnets with disorder. We also discuss the implications of our results for the square-lattice compound Sr2CuTe1−xWxO6.
About the speaker
Dr. Gong received his Ph. D. in the University of Chinese Academy of Sciences, supervised by Prof. Gang Su. After that, Dr. Gong did his postdoctoral research in the California State University Northridge and the National High Magnetic Field Laboratory. His research interests are focused on the novel phases in strongly correlated electronic systems including quantum spin liquid, fractional quantum Hall effects, and unconventional superconductivity. Recently, he is also working on the novel phases driven by disorder in frustrated antiferromagnets and doped Mott insulators.