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Title: Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry

The realization of quantum spin Hall effect in HgTe quantum wells is considered a milestone in the discovery of topological insulators. Quantum spin Hall states are predicted to allow current flow at the edges of an insulating bulk, as demonstrated in various experiments. A key prediction yet to be experimentally verified is the breakdown of the edge conduction under broken time-reversal symmetry. Here we first establish a systematic framework for the magnetic field dependence of electrostatically gated quantum spin Hall devices. We then study edge conduction of an inverted quantum well device under broken time-reversal symmetry using microwave impedance microscopy, and compare our findings to a non-inverted device. At zero magnetic field, only the inverted device shows clear edge conduction in its local conductivity profile, consistent with theory. Surprisingly, the edge conduction persists up to 9 T with little change. Finally, this indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.
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  1. Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); Univ. Wurzburg, Wurzburg (Germany)
  3. Univ. Wurzburg, Wurzburg (Germany)
  4. Stanford Univ., Stanford, CA (United States); Univ. of Texas, Austin, TX (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-76SF00515; PHY-0830228; DMR1305731; FP7-PEOPLE-2010-274769
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Stanford Univ., CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States