TY  - EJOUR
AU  - Leis, Arthur
AU  - Schleenvoigt, Michael
AU  - Cherepanov, Vasily
AU  - Lüpke, Felix
AU  - Schüffelgen, Peter
AU  - Mussler, Gregor
AU  - Grützmacher, Detlev
AU  - Voigtländer, Bert
AU  - Tautz, F. Stefan
TI  - Lifting the spin-momentum locking in ultra-thin topological insulator films
PB  - arXiv
M1  - FZJ-2025-02322
PY  - 2021
AB  - Three-dimensional (3D) topological insulators (TIs) are known to carry 2D Dirac-like topological surface states in which spin-momentum locking prohibits backscattering. When thinned down to a few nanometers, the hybridization between the topological surface states at the top and bottom surfaces results in a topological quantum phase transition, which can lead to the emergence of a quantum spin Hall phase. Here, we study the thickness-dependent transport properties across the quantum phase transition on the example of (Bi$_{0.16}$Sb$_{0.84}$)$_2$Te$_3$ films, with a four-tip scanning tunnelling microscope. Our findings reveal an exponential drop of the conductivity below the critical thickness. The steepness of this drop indicates the presence of spin-conserving backscattering between the top and bottom surface states, effectively lifting the spin-momentum locking and resulting in the opening of a gap at the Dirac point. Our experiments provide crucial steps towards the detection of quantum spin Hall states in transport measurements.
KW  - Mesoscale and Nanoscale Physics (cond-mat.mes-hall) (Other)
KW  - FOS: Physical sciences (Other)
LB  - PUB:(DE-HGF)25
DO  - DOI:10.48550/ARXIV.2106.06217
UR  - https://juser.fz-juelich.de/record/1041583
ER  -