#### 电子赌城官方大厅“博约学术论坛”系列报告-第284期

­电子赌城官方大厅博约学术论坛系列报告

284

 题目：Response of a strongly interacting spin-orbit coupling system to a Zeeman field : Topological quantum spin liquid or not? 报告人：叶锦武 教授（美国密西西比州立大学）           时 间：2021年5月11日(周二) 下午14:00-16:00地 点：中心教学楼620室 摘要：Recently, there are flurries of theoretical and experimental researches to investigate the response of so called Kitaev materials to a Zeeman field. The most inspiring and provocative experiment is by Y. Kasahara, {\sl et.al}, Y. Matsuda, entitled " Majorana quantization and half-integer thermal quantum Hall effect in a Kitaev spin liquid, Nature 559, 227-231 (2018)." In this work, starting from general symmetry principle, we construct various effective actions to study the response to a longitudinal Zeeman field of a strongly interacting spinor atom with a 2 dimensional (2d) anisotropic Rashba type of spin orbital coupling (SOC) in a square lattice. We find the interplay between the Zeeman field and the SOC leads to rich and novel classes of quantum commensurate (C-) and in-commensurate (IC-) phases, exotic excitations and novel quantum phase transitions (QPT). These phases include the collinear gapped Z-x at low Zeeman field, collinear gapped Z-FM at high Zeeman field, gapless co-planar canted phase at low SOC and gapless non-coplanar IC-Skyrmion crystal (IC-SkX) at large SOC in intermediate Zeeman fields. We also discover several novel classes of quantum phase transitions with dynamic exponents $z=1, z=2$ and anisotropic ones $(z_x=3/2, z_y=3)$ respectively. We argue that it is the exotic form of the gapless excitations in the canted or IC-SkX phase which leads to the un-quantized thermal Hall conductivities even at zero temperature limit. We give critical discussions on SOC materials such as Chiral magnets MnSi, Fe$_{0.5}$Co$_{0.5}$Si, especially 4d Kitaev materials $\alpha$-RuCl$_3$ in a Zeeman field. 简历：叶锦武教授是美国耶鲁大学理论物理博士。现在是美国密西西比州立大学教授。叶教授主要研究领域是强相互作用的电子、玻色子、自旋、光子等的合作现象和量子或拓扑相变理论，他的研究还涉及超对称性破缺、共形场论和各种量子或拓扑相的量子引力对偶。He is currently visiting TD Lee institute in Shanghai. His two most recent research directions are on(1) Topological Phases,topological phase transitions driven by interactions in various spin-orbit coupled systems.(2) Quantum chaos and quantum information scramblings in cavity QED systems or in Sachdev-Ye-Kitaev (SYK) models. Connections between SYK models, conformal field theory and topological phases. 联系方式：yangfan _blg@bit.edu.cn邀请人：杨帆 教授网 址：http:/承办单位：物理学院、先进光电量子结构设计与测量教育部重点实验室