Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 55: Topology and symmetry protected materials & Topological insulators (joint session O/HL/TT)
TT 55.9: Talk
Wednesday, March 11, 2026, 17:00–17:15, HSZ/0401
Quantized Subband Tunneling from Topological Insulator Nanowire Scanning Probe Tips — •Abhisek Kole1,2, Felix Münning3,4, Xiaosheng Yang1,5, Jia G. Lu6, Oliver Breunig4, F. Stefan Tautz1,2, Yoichi Ando4, and Felix Lüpke1,4 — 1Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany — 2Institute for Experimental Physics IV A, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany — 3Institute of Physics I, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — 4Institute of Physics II, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — 5School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China — 6Department of Physics/Electrophysics, University of Southern California, Los Angeles, CA 90089, USA
In topological insulator nanowires, the interplay between size quantization and the surface states wrapping the nanowire circumference gives rise to a magnetic-flux-tunable band structure. We demonstrate the controlled fabrication of (Bi_(1-x) Sb_x )_2 Te_3 (BST) topological insulator nanowires into scanning tunneling microscopy tips. Tunneling spectroscopy reveals a series of distinct peak-like features that exhibit a characteristic 1D DOS, indicating tunneling into the quantized 1D subbands of the BST nanowire tips. Furthermore, a magnetic-field-induced gap-closing and reopening transition is observed, consistent with the Dirac-like gap-closing transition expected for such wires. Moreover, we find indications of spin-selective helical tunneling between the nanowire tip and the Rashba surface states of Au(111).
Keywords: Topological insulator nanowires; Quantized 1D tunneling; Scanning tunneling spectroscopy (STM); Helical spin-selective tunneling; Flux-tunable Dirac subbands