TY  - EJOUR
AU  - Leis, Arthur
AU  - Schleenvoigt, Michael
AU  - Moors, Kristof
AU  - Soltner, Helmut
AU  - Cherepanov, Vasily
AU  - Schüffelgen, Peter
AU  - Mussler, Gregor
AU  - Grützmacher, Detlev
AU  - Voigtländer, Bert
AU  - Lüpke, Felix
AU  - Tautz, F. Stefan
TI  - Probing edge state conductance in ultra-thin topological insulator films
PB  - arXiv
M1  - FZJ-2025-02320
PY  - 2022
AB  - Quantum spin Hall (QSH) insulators have unique electronic properties, comprising a band gap in their two-dimensional interior and one-dimensional spin-polarized edge states in which current flows ballistically. In scanning tunneling microscopy (STM), the edge states manifest themselves as a localized density of states. However, there is a significant research gap between the observation of edge states in nanoscale spectroscopy, and the detection of ballistic transport in edge channels which typically relies on transport experiments with microscale lithographic contacts. Here, we study few-layer films of the three-dimensional topological insulator (Bi$_{x}$Sb$_{1-x})_2$Te$_3$, for which a topological transition to a two-dimensional topological QSH insulator phase has been proposed. Indeed, an edge state in the local density of states is observed within the band gap. Yet, in nanoscale transport experiments with a four-tip STM, 2 and 3 quintuple layer films do not exhibit a ballistic conductance in the edge channels. This demonstrates that the detection of edge states in spectroscopy can be misleading with regard to the identification of a QSH phase. In contrast, nanoscale multi-tip transport experiments are a robust method for effectively pinpointing ballistic edge channels, as opposed to trivial edge states, in quantum materials.
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.2204.03753
UR  - https://juser.fz-juelich.de/record/1041581
ER  -