Abstract: Kalmeyer-Laughlin (KL) chiral spin liquid (CSL) is a type of quantum spin liquid without time-reversal symmetry, and it is considered as the parent state of an exotic type of superconductor—anyon superconductor. Such an exotic state has been sought for about thirty years; however, it remains unclear whether it can exist in a realistic system where time-reversal symmetry is breaking spontaneously. By using the density matrix renormalization group, we show that KL CSL exists in frustrated anisotropic kagome antiferromagnetic models, which have time-reversal symmetry breaking. We find that these models may have two topological degenerate ground states, which exhibit nonvanishing scalar chirality order and are protected by finite excitation gap. Furthermore, we identify this state as KL CSL by the characteristic edge conformal field theory from the entanglement spectrum and the quasiparticles braiding statistics extracted from the modular matrix. Also we obtain the time-reversal invariant spin liquid by tuning the interactions, and we show the continuous phase transition between two spin liquids. Finally we discuss the possible implication of our results on the nature of spin liquid in nearest neighbor XXZ kagome antiferromagnets, including the most studied nearest-neighbor kagome anti-ferromagnetic Heisenberg model.     

 

报告人简介: 陈焱, 南京大学学士 (1993)、博士 (1998)；美国休斯顿大学德州超导中心博士后及Research Associate(1998-2003); 香港大学物理系助理教授(研究)(2003-2007), 荣誉助理教授(2003-2009), 及荣誉副教授 (2009-至今)。陈焱教授2007年9月加入复旦大学, 现为复旦大学先进材料实验室PI 研究员、博士生导师, 首届上海高校特聘教 (东方学者)。主要从事关联多体系统电子态性质的理论研究, 特别是高温超导铜氧化物的杂质态和混合态方面。此外, 在有机超导体的绝缘态到超导态的相变, 超冷原子系统中的奇异超流态, 关联多体系统中的量子纠缠与量子相变等方面取得了较有影响的研究成果。