陈焱教授
复旦大学物理系
时间：2014年10月24日（星期五）下午3:30
地点：唐仲英楼B501
摘要：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 exotic anyon superconductor. Such an exotic state has been sought for more than twenty 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 a frustrated anisotropic kagome antiferromagnets, which has time-reversal symmetry breaking. We find that our model has 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. Next we study spin-liquid phases of spin-1/2 XXZ kagome antiferromagnets. We find that the emergence of the spin-liquid phase is independent of the anisotropy of the XXZ interaction. In particular, the two extreme limits---the Ising and the XY---host the same spin-liquid phases as the isotropic Heisenberg model. Both a time-reversal-invariant spin liquid and a chiral spin liquid are obtained. We show that they evolve continuously into each other by tuning the second- and the third-neighbor interactions.
1993年南京大学学士，1998年南京大学博士。1998-2003年美国休斯顿大学德州超导中心博士后及Research Associate，2003-2007年香港大学物理系助理教授(研究)，2007年底至今任教于复旦大学,首届上海高校特聘教授。现任复旦大学物理系副主任、应用表面物理国家重点实验室副主任。从事复杂量子体系中新奇量子态的理论研究，主要工作领域包括量子磁性、非常规超导电性、关联拓扑量子态等。迄今发表SCI 论文约70 篇，其中Phys. Rev. Lett. 10篇，Phys. Rev.系列近40 篇。担任中国物理学会凝聚态理论及统计物理专业委员会秘书长，国际学术刊物Philosophical Magazine及Philosophical Magazine Letters的副主编， Springer Tracts in Modern Physics系列丛书的编辑等。