Gapped Dirac cones and spin texture in thin film topological insulator

Abstract

The protected surface states of topological insulators (TIs) form gapless Dirac cones corresponding non-degenerate eigenstates with helical spin polarisation. The presence of a warping term deforms the isotropic cone of the most simple model into snowflake Fermi surfaces as in Bi2Se3 and Bi2Te3. Their features have been identified in STM quasiparticle interference (QPI) experiments on isolated surfaces. Here we investigate the QPI spectrum for the TI thin-film geometry with finite tunnelling between the surface states. This leads to a dramatic change of spectrum due to gapping and a change in spin texture that should leave distinct signatures in the QPI pattern. We consider both normal and magnetic exchange scattering from the surface impurities and obtain the scattering t-matrix in Born approximation as well as the general closed solution. We show the expected systematic variation of QPI snowflake intensity features by varying film thickness and study, in particular, the influence on backscattering processes. We predict the variation of the QPI spectrum for Bi2Se3 thin films using the observed gap dependence from ARPES results.

16 pages, 13 figures

References in corpus (7)

• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• Intrinsic conduction through topological surface states of insulating Bi${}_2$Te${}_3$ epitaxial thin films
• Stationary phase approximation approach to the quasiparticle interference on the surface of a strong topological insulator
• Spin-orbit scattering visualized in quasiparticle interference
• Quasiparticle interference from magnetic impurities
• Topological phases of topological insulator thin films
• Ab-initio Theory of Fourier-transformed Quasiparticle Interference Maps and Application to the Topological Insulator Bi${}_2$Te${}_3$

Cited by in corpus (9)

• Finite-size Topology
• Magnetic warping in topological insulators
• Fermi surface segmentation in the helical state of a Rashba superconductor
• Momentum relaxation effects in 2D-Xene field effect device structures
• Surface step states and Majorana end states in profiled topological insulator thin films
• Quasiparticle scattering in three-dimensional topological insulators near the thickness limit
• Image of helical local moment magnetic order in the STM spectrum
• Spatial aspects of spin polarization of structurally split surface states in thin films with magnetic exchange and spin-orbit interaction
• Magnetic excitations in the helical Rashba superconductor