SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Poster Session: Topology

TT 59.3: Poster

Donnerstag, 30. März 2023, 15:00–18:00, P2/OG4

Quantum transport through resonant Dirac states in topological insulator nanowire constrictions — •Michael Barth¹, Maximilian Fürst¹, Cosimo Gorini², and Klaus Richter¹ — ¹Institute of Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany — ²Université Paris-Saclay, CEA, CNRS, SPEC, 91191, Gif-sur-Yvette, France

Quantum transport in topological insulator (TI) nanowires is expected to be mediated by surface states which wrap phase coherently around the circumference [1]. The spectrum corresponds to a quantized and gapped Dirac cone, where the gap is present because of a Berry phase of π which arises due to spin-momentum locking. In this work, we numerically study transport in TI constrictions which are subjected to an axial magnetic field. More specifically, we consider a realistic junction of a narrow TI wire which is smoothly connected at its two ends to broad TI leads and calculate the transmission through the setup with respect to the Fermi energy and the magnetic field. The latter is tuned to close the Berry gap [2]. It turns out, that perpendicular field components in the constriction lead to the formation of magnetic barriers which result in resonant Dirac states. The proposed system can be used to spectroscopically study the Dirac spectrum with respect to its gate and flux dependence. Moreover, different transport regimes are identified, which depend on the length of the central wire segment.
[1] J. H. Bardarson, P. W. Brouwer, and J. E. Moore Phys. Rev. Lett. 105, 156803 (2010)
[2] J. Ziegler et al., Phys. Rev. B 97, 035157 (2018)