Orbit- and Atom-Resolved Spin Textures of Intrinsic, Extrinsic and Hybridized Dirac Cone States

TL;DR

This study combines calculations and spectroscopy to reveal consistent helical spin textures across various Dirac cone states in topological insulator systems, emphasizing the role of spin-orbit coupling.

Contribution

It provides a detailed orbit- and atom-resolved analysis of spin textures in intrinsic, extrinsic, and hybridized Dirac states, highlighting their common spin-orbit coupling origin.

Findings

Spin textures are identical for different Dirac cone states.

s and pz orbitals have clockwise or counterclockwise spin rotation.

px and py orbitals exhibit additional radial spin components.

Abstract

Combining first-principles calculations and spin- and angle-resolved photoemission spectroscopy measurements, we identify the helical spin textures for three different Dirac cone states in the interfaced systems of a 2D topological insulator (TI) of Bi(111) bilayer and a 3D TI Bi2Se3 or Bi2Te3. The spin texture is found to be the same for the intrinsic Dirac cone of Bi2Se3 or Bi2Te3 surface state, the extrinsic Dirac cone of Bi bilayer state induced by Rashba effect, and the hybridized Dirac cone between the former two states. Further orbit- and atom-resolved analysis shows that s and pz orbits have a clockwise (counterclockwise) spin rotation tangent to the iso-energy contour of upper (lower) Dirac cone, while px and py orbits have an additional radial spin component. The Dirac cone states may reside on different atomic layers, but have the same spin texture. Our results suggest that the unique spin texture of Dirac cone states is a signature property of spin-orbit coupling, independent of topology.