Approaching quantization in macroscopic quantum spin hall devices through gate training

Lukas Lunczer (Corresponding author), Philipp Leubner, Martin Endres, Valentin L. Müller, Christoph Brüne, Hartmut Buhmann, Laurens W. Molenkamp

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Quantum spin Hall edge channels hold great promise as dissipationless one-dimensional conductors. However, the ideal quantized conductance of 2e2/h is only found in very short channels-in contradiction with the expected protection against backscattering of the topological insulator state. In this Letter we show that enhancing the band gap does not improve quantization. When we instead alter the potential landscape by charging trap states in the gate dielectric using gate training, we approach conductance quantization for macroscopically long channels. Effectively, the scattering length increases to 175 μm, more than 1 order of magnitude longer than in previous works for HgTe-based quantum wells. Our experiments show that the distortion of the potential landscape by impurities, leading to puddle formation in the narrow gap material, is the major obstacle for observing undisturbed quantum spin Hall edge channel transport.

LanguageEnglish
Article number047701
Number of pages5
JournalPhysical Review Letters
Volume123
Issue number4
DOIs
StatePublished - 22 Jul 2019

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Lunczer, L., Leubner, P., Endres, M., Müller, V. L., Brüne, C., Buhmann, H., & Molenkamp, L. W. (2019). Approaching quantization in macroscopic quantum spin hall devices through gate training. Physical Review Letters, 123(4), [047701]. DOI: 10.1103/PhysRevLett.123.047701
Lunczer, Lukas ; Leubner, Philipp ; Endres, Martin ; Müller, Valentin L. ; Brüne, Christoph ; Buhmann, Hartmut ; Molenkamp, Laurens W./ Approaching quantization in macroscopic quantum spin hall devices through gate training. In: Physical Review Letters. 2019 ; Vol. 123, No. 4.
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Lunczer, L, Leubner, P, Endres, M, Müller, VL, Brüne, C, Buhmann, H & Molenkamp, LW 2019, 'Approaching quantization in macroscopic quantum spin hall devices through gate training' Physical Review Letters, vol. 123, no. 4, 047701. DOI: 10.1103/PhysRevLett.123.047701

Approaching quantization in macroscopic quantum spin hall devices through gate training. / Lunczer, Lukas (Corresponding author); Leubner, Philipp; Endres, Martin; Müller, Valentin L.; Brüne, Christoph; Buhmann, Hartmut; Molenkamp, Laurens W.

In: Physical Review Letters, Vol. 123, No. 4, 047701, 22.07.2019.

Research output: Contribution to journalArticleAcademicpeer-review

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Lunczer L, Leubner P, Endres M, Müller VL, Brüne C, Buhmann H et al. Approaching quantization in macroscopic quantum spin hall devices through gate training. Physical Review Letters. 2019 Jul 22;123(4). 047701. Available from, DOI: 10.1103/PhysRevLett.123.047701