拓扑半金属的角分辨光电子能谱研究

Angle-resolved photoemission spectroscopy studies of topological semimetals

拓扑半金属是一类新奇的量子材料,它存在受拓扑保护的无能隙体态能带交叉和特征表面态.根据能带交叉的维度和简并度,拓扑半金属可以简单分为:零维的四重简并狄拉克半金属、二重简并外尔半金属、三重/六重/八重简并点半金属,和高维度的节线/节面半金属.近十年来,基于角分辨光电子能谱(ARPES)实验技术,人们可以直接测量拓扑半金属中的体态能带简并和特征表面态,清楚地揭示材料的拓扑本质.本文系统性回顾了使用ARPES研究各种类拓扑半金属的成果与进展,有助于理解其物理性质、拓扑起源以及探索更多新奇拓扑半金属.

Topological semimetals(TSMs)are a class of novel quantum materials with gapless bulk band crossings and characteristic surface states protected by nontrivial topology.Based on the dimension and degeneracy of band crossings,TSMs can be divided into zero-dimensional four-folding degenerate Dirac,two-folding degenerate Weyl,three-/six-/eight-folding degenerate,and high-dimensional nodal-line/surface semimetals.In the past decade,researchers have measured the bulk band crossings and characteristic surface states of TSMs through angle-resolved photoemission spectroscopy(ARPES)to clearly reveal the topological nature of these TSMs.In this article,we systematically review the achievements and advances of ARPES studies of TSMs.This review will help us understand the physical properties and topological origins and facilitate the exploration of more novel TSMs.