Gapped Surface States in a Strong-Topological-Semimetal

Abstract

A three-dimensional strong-topological-insulator or -semimetal hosts topological surface states which are often said to be gapless so long as time-reversal symmetry is preserved. This narrative can be mistaken when surface state degeneracies occur away from time-reversal-invariant momenta. The mirror-invariance of the system then becomes essential in protecting the existence of a surface Fermi surface. Here we show that such a case exists in the strong-topological-semimetal Bi${}_4$Se${}_3$. Angle-resolved photoemission spectroscopy and \textit{ab initio} calculations reveal partial gapping of surface bands on the Bi${}_2$Se${}_3$-termination of Bi${}_4$Se${}_3$(111), where an 85 meV gap along $\bar{\Gamma }\bar{K}$ closes to zero toward the mirror-invariant $\bar{\Gamma }\bar{M}$ azimuth. The gap opening is attributed to an interband spin-orbit interaction that mixes states of opposite spin-helicity.

arXiv comment5 pages, 3 figures

References in corpus (20)

• Topological Insulators
• Topological insulators and superconductors
• Topological Insulators in Three Dimensions
• Topological Insulators with Inversion Symmetry
• Topological Crystalline Insulators
• Topological Insulator Materials
• Topological Crystalline Insulators in the SnTe Material Class
• First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
• Giant Spin-splitting in the Bi/Ag(111) Surface Alloy
• Hexagonal Warping Effects in the Surface States of Topological Insulator Bi${}_2$Te${}_3$
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Three-Dimensional Topological Insulators
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• Non-trivial spin-texture of the coaxial Dirac cones on the surface of topological crystalline insulator SnTe
• Novel Spin-texture on the warped Dirac-cone surface states in topological insulators
• Topological insulator in a Bi-Bi${}_2$Se${}_3$ infinitely adaptive superlattice phase
• Termination dependent topological surface states of the natural superlattice phase Bi${}_4$Se${}_3$
• Direct Observation of Interband Spin-Orbit Coupling in a Two-Dimensional Electron System
• Surface states on a topologically non-trivial semimetal: The case of Sb(110)
• Interband spin-orbit coupling between anti-parallel spin states in Pb quantum well states

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• Robust Dual Topological Character with Spin-Valley Polarization in a Monolayer of the Dirac Semimetal Na${}_3$Bi
• Spin-polarization control driven by a Rashba-type effect breaking the mirror symmetry in two-dimensional dual topological insulators
• A strong-topological-metal material with multiple Dirac cones
• Dual Topological Insulator Device with Disorder Robustness
• Surface states of gapped electron systems and semi-metals