%0 Journal Article
%A Leis, Arthur
%A Schleenvoigt, Michael
%A Cherepanov, Vasily
%A Lüpke, Felix
%A Schüffelgen, Peter
%A Mussler, Gregor
%A Grützmacher, Detlev
%A Voigtländer, Bert
%A Tautz, F. Stefan
%T Lifting the Spin‐Momentum Locking in Ultra‐Thin Topological Insulator Films
%J Advanced quantum technologies
%V 4
%N 11
%@ 2511-9044
%C Weinheim
%I Wiley-VCH Verlag
%M FZJ-2021-03711
%P 2100083 -
%D 2021
%X 3D topological insulators 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, the thickness-dependent transport properties across the quantum phase transition are studied on the example of (Bi0.16Sb0.84.)2Te3 films, with a four-tip scanning tunneling microscope. The 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. The experiments provide a crucial step toward the detection of quantum spin Hall states in transport measurements.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000695620900001
%R 10.1002/qute.202100083
%U https://juser.fz-juelich.de/record/897249