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TT: Fachverband Tiefe Temperaturen

TT 74: Topological Insulators

TT 74.1: Vortrag

Donnerstag, 21. März 2024, 15:00–15:15, H 3005

Gapped Dirac cones in thin film topological insulator — •Alireza Akbari¹ and Peter Thalmeier² — ¹Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany — ²Max Planck Institute for the Chemical Physics of Solids, 01187 Dresden, Germany

Topological insulators (TIs) have gapless Dirac cones with helical spin polarization in their surface states. Warping introduces snowflake Fermi surfaces, observed in materials like Bi₂Se₃ and Bi₂Te₃ . Quasiparticle interference (QPI) experiments on isolated TI surfaces reveal distinct features. In thin film geometries with finite tunneling between surface states, the QPI spectrum undergoes significant changes, leading to gap formation and altered spin texture. We explore variations with film thickness and their impact on backscattering processes. Introducing a step in the TI film, achieved by profiling the substrate, results in one-dimensional bound states within the hybridization gap. In an s-wave superconductor substrate, Majorana zero modes appear at step ends within the superconducting gap. Thus this simple configuration of a stepped interface between a superconductor and a TI may host Majorana zero modes effectively.

[1] Phys. Rev. Research 2 (2020) 033002.

[2] Phys. Rev. B 104 (2021) 184511.

Keywords: Dirac fermions; Impurities; Spin-orbit coupling; Thin film Topological insulators; Majorana zero modes