题目：Spin-Resolved Topological Phases and Material Realizations

报告人：王志俊 中国科学院物理研究所

时间：2026年10月13日（星期二）10:00-11:30

地点：郭可信楼301室

报告摘要：

Recent discoveries in three-dimensional topological crystalline insulators (TCIs) have unveiled novel spin-resolved phases: 3D quantum spin Hall insulators (QSHIs), “spin-Weyl” semimetals, and T-doubled axion insulator (T-DAXI) states with nontrivial partial axion angles indicative of a 3D spin-magnetoelectric bulk response and half-quantized 2D TI surface states originating from a partial parity anomaly. First, we discover that inversion-symmetry indicated helical HOTIs realize one of three spin-resolved phases. Supported by ab-initio calculations and STM measurements, we demonstrate that bulk α-Bi4I4 (SG C2/m) with trivial symmetry indicators hosts 3D QSHI with robust helical edge states, whose topology originates solely from a nonzero spin Chern number. Our results provide a pathway for realizing nearly quantized spin Hall conductivity per unit cell in a bulk crystal.

Second, we explore how T-DAXI phases are protected by nonsymmorphic symmetries (glide or screw). In nonsymmorphic TCIs (δh =1 or δs = 1), partial axion angles for some spin directions are quantized by the symmetries (gy or s2T). This topology yields a novel topological spin magnetoelectric effect. Using ab-initio calculations, we demonstrate that mixed bismuth monohalides Bi4Br3I (or Bi4BrI3) synthesized in space group Cmc21 is a nonsymmorphic TCI, realizing the symmetry-indicated T-DAXI phase. Our findings not only establish a new paradigm for nonsymmorphic topological states but also introduce a highly promising platform for purely spin-based topological quantum devices.

报告人简介：

王志俊博士在2014年获得中国科学院物理研究所理学博士学位，随后在美国普林斯顿大学物理系从事博士后研究工作，2018年回到中国科学院物理研究所工作，现为博士生导师，研究员。主要从事计算凝聚态物理领域的研究，包括拓扑半金属、磁性拓扑、本征拓扑超导和激子绝缘态。建立了拓扑能带表示理论和新型费米子理论，发展不可约表示和拓扑材料计算软件包(TopMat.org)，成功计算发现了多种新奇拓扑量子材料，如狄拉克半金属Na3Bi、本征拓扑超导Fe(Se,Te)、三重费米子CoSi和激子绝缘体Ta2Pd3Te5等。迄今共发表SCI论文100余篇，被引用2万余次，个人H 因子54。2019至今连续六年入选科睿唯安 “全球高被引科学家”物理领域榜单。成果入选两院院士评选的“2019年度中国十大科技进展新闻”，获得2020年IUPAP(C20)的“计算物理青年科学家奖”，2023年度国家自然科学奖一等奖（第五），2024年度中国科学院青年科学家奖。