Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction

M. R. Calvo, F. De Juan, R. Ilan, E. J. Fox, A. J. Bestwick, M. Mühlbauer, J. Wang, C. Ames, P. Leubner, C. Brüne, S. C. Zhang, H. Buhmann, L. W. Molenkamp, D. Goldhaber-Gordon

Research output: Contribution to journalArticlepeer-review

Abstract

We study the electronic transport across an electrostatically gated lateral junction in a HgTe quantum well, a canonical 2D topological insulator, with and without an applied magnetic field. We control the carrier density inside and outside a junction region independently and hence tune the number and nature of 1D edge modes propagating in each of those regions. Outside the bulk gap, the magnetic field drives the system to the quantum Hall regime, and chiral states propagate at the edge. In this regime, we observe fractional plateaus that reflect the equilibration between 1D chiral modes across the junction. As the carrier density approaches zero in the central region and at moderate fields, we observe oscillations in the resistance that we attribute to Fabry-Perot interference in the helical states, enabled by the broken time reversal symmetry. At higher fields, those oscillations disappear, in agreement with the expected absence of helical states when band inversion is lifted.

Original languageEnglish
Article number226401
JournalPhysical Review Letters
Volume119
Issue number22
DOIs
StatePublished - 29 Nov 2017

Funding

FundersFunder number
EU ERC-AG3-TOP
National Thousand-Young-Talents Program
VITI
National Science FoundationPHY-0830228, 0830228
U.S. Department of Energy
Air Force Office of Scientific Research
Defense Advanced Research Projects Agency
Office of Science
Basic Energy Sciences
Seventh Framework Programme274769
Division of Materials Sciences and EngineeringDE-AC02-76SF00515
European CommissionFP7-PEOPLE-2010-274769
Deutsche Forschungsgemeinschaft
National Natural Science Foundation of China11774065
Elitenetzwerk Bayern
Helmholtz Association

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