【大学频道】北京大学量子材料科学中心呈献 | 中国人民大学刘正鑫教授

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题   目：Quantum Spin Liquid Phases in Extended Kitaev Model报告人：刘正鑫单   位：中国人民大学时   间：2019-09-11地   点：北京大学

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报告摘要

The Kitaev model on the honeycomb lattice offers exactly soluble examples of both gapped and gapless quantum spin liquids (QSLs). In addition to the Kitaev (K) interaction, candidate Kitaev materials also possess Heisenberg (J) and off-diagonal symmetric (Gamma) couplings. We investigate the quantum spin-1/2 K-J-Gamma model on the honeycomb lattice by a variational Monte Carlo (VMC) method. In addition to the Kitaev spin liquid (KSL) phase, we find that there is one proximate Kitaev Spin Liquid (PKSL) phase, while the rest of the phase diagram contains different magnetically ordered states. The KSL is known as a gapless state with 2 Majorana cones and a (almost) gapped spin response. In contrast, the PKSL has 14 Majorana cones and a gapless spin response. In a magnetic field applied normal to the honeycomb plane, it realizes two of Kitaev's gapped chiral spin-liquid states, namely, a non-Abelian phase with Chern number 5 and an Abelian phase with Chern number 4. The experimental characters of the chiral spin liquids are their thermal Hall conductances. Our phase diagram provides a clue in understanding the physics of candidate Kitaev materials.

个人简介

Prof. Zheng-Xin Liu received his Ph.D in the Hong Kong University of Science and Technology in 2010. After that he worked in the Institute for Advanced Study in Tsinghua University as a post doctor and then as an associate member. He joined Renmin University of China in 2015 as an associate professor. Prof. Liu's research area includes symmetry protected topological phases, quantum magnetism, and many-body numerical computations. Recently, his interests are focused on the magnetic systems, including quantum spin liquid (such as Kitaev spin liquid) and magnetic semimetals.

—— ——往期精彩回顾—— ——● 北京大学量子材料科学中心呈献 | 普林斯顿大学张骏祎：Dipolar Dimer Liquid● 北京大学量子材料科学中心呈献 | 东京大学龚宗平博士：Topological phases of non-Hermitian systems● 北京大学量子材料科学中心呈献 | Yonglong Xie of Princeton University: Visualizing topological and correlated phases with a scanning tunneling microscope● 北京大学量子材料科学中心呈献 | 犹他大学黄华卿研究员：Theoretically Tracing Topological States: from crystals to quasicrystals and to noncrystalline systems● 北京大学量子材料科学中心呈献 | Hengyun Zhou of Harvard University：Surpassing the Interaction Limit to Quantum Metrology with Fault-Tolerant Control● 北京大学量子材料科学中心呈献 | Gang Cao：Control of Quantum States in 4d/5d Transition Metal Oxides● 北京大学量子材料科学中心呈献 | Patrick Rinke：The Artist: Artificial Intelligence for Spectroscopy
● 北京大学量子材料科学中心呈献 | 佛罗里达大学张晓光教授：Multi-phonon processes in solids from first-principles● 北京大学量子材料科学中心呈献 | 中国科学技术大学翟晓芳研究员：Complex oxide thin films and heterostructures for novel physics and applications● 北京大学量子材料科学中心呈献 | Michael S. Fuhrer：Topological materials for low-energy electronics

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