Seminar: Exploring Chiral and Time-reversal Invariant Spin Liquids in Kagome Antiferromagnets

Professor Yan CHEN (Department of Physics, Fudan University) is going to give a seminar at 2pm on September 21, 2015 at teaching building number 12-423 in Yuquan Campus. Below is the abstract of the seminar.

Exploring Chiral and Time-reversal Invariant Spin Liquids in Kagome Antiferromagnets
Prof. Yan CHEN
Department of Physics, Fudan University

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 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. At last, our preliminary results on the hole-doped chiral spin liquids will be discussed.
Time: 2 pm, Monday, September 21, 2015
Place: Room 423, teaching building number 12, Yuquan Campus