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

Abstract

Here, we study the electronic transport across an electrostatically-gated lateral junction in a HgTe quantum well, a canonical 2D topological insulator, with and without applied magnetic field. We control 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 2D gap, magnetic field drives the system to the quantum Hall regime, and chiral states propagate at the edge. In this regime, we observe fractional plateaus which reflect the equilibration between 1D chiral modes across the junction. As carrier density approaches zero in the central region and at moderate fields, we observe oscillations in 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.

Authors:
 [1];  [2];  [3];  [4];  [4];  [5];  [6];  [5];  [5];  [5];  [4];  [5];  [5];  [4]
  1. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); CIC nanoGUNE, Donostia-San Sebastian (Spain); Ikerbasque, Bilbao (Spain)
  2. Tel Aviv Univ., Tel Aviv (Israel); Oxford Univ. (United Kingdom)
  3. Tel Aviv Univ., Tel Aviv (Israel); Univ. of California, Berkeley, CA (United States)
  4. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Univ. Wurzburg, Wurzburg (Germany)
  6. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fundan Univ., Shanghai (China)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Natural Science Foundation of China (NNSFC); National Science Foundation (NSF)
OSTI Identifier:
1408919
Alternate Identifier(s):
OSTI ID: 1410580
Grant/Contract Number:  
AC02-76SF00515; PHY-0830228; 11774065
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 119; Journal Issue: 22; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Calvo, M. R., de Juan, F., Ilan, R., Fox, E. J., Bestwick, A. J., Mühlbauer, M., Wang, J., Ames, C., Leubner, P., Brune, C., Zhang, S. C., Buhmann, H., Molenkamp, L. W., and Goldhaber-Gordon, David. Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.119.226401.
Calvo, M. R., de Juan, F., Ilan, R., Fox, E. J., Bestwick, A. J., Mühlbauer, M., Wang, J., Ames, C., Leubner, P., Brune, C., Zhang, S. C., Buhmann, H., Molenkamp, L. W., & Goldhaber-Gordon, David. Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction. United States. doi:10.1103/PhysRevLett.119.226401.
Calvo, M. R., de Juan, F., Ilan, R., Fox, E. J., Bestwick, A. J., Mühlbauer, M., Wang, J., Ames, C., Leubner, P., Brune, C., Zhang, S. C., Buhmann, H., Molenkamp, L. W., and Goldhaber-Gordon, David. Wed . "Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction". United States. doi:10.1103/PhysRevLett.119.226401. https://www.osti.gov/servlets/purl/1408919.
@article{osti_1408919,
title = {Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction},
author = {Calvo, M. R. and de Juan, F. and Ilan, R. and Fox, E. J. and Bestwick, A. J. and Mühlbauer, M. and Wang, J. and Ames, C. and Leubner, P. and Brune, C. and Zhang, S. C. and Buhmann, H. and Molenkamp, L. W. and Goldhaber-Gordon, David},
abstractNote = {Here, we study the electronic transport across an electrostatically-gated lateral junction in a HgTe quantum well, a canonical 2D topological insulator, with and without applied magnetic field. We control 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 2D gap, magnetic field drives the system to the quantum Hall regime, and chiral states propagate at the edge. In this regime, we observe fractional plateaus which reflect the equilibration between 1D chiral modes across the junction. As carrier density approaches zero in the central region and at moderate fields, we observe oscillations in 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.},
doi = {10.1103/PhysRevLett.119.226401},
journal = {Physical Review Letters},
number = 22,
volume = 119,
place = {United States},
year = {2017},
month = {11}
}

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