TY - JOUR
T1 - Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry
AU - Ma, Eric Yue
AU - Calvo, M. Reyes
AU - Wang, Jing
AU - Lian, Biao
AU - Mühlbauer, Mathias
AU - Brüne, Christoph
AU - Cui, Yong Tao
AU - Lai, Keji
AU - Kundhikanjana, Worasom
AU - Yang, Yongliang
AU - Baenninger, Matthias
AU - König, Markus
AU - Ames, Christopher
AU - Buhmann, Hartmut
AU - Leubner, Philipp
AU - Molenkamp, Laurens W.
AU - Zhang, Shou Cheng
AU - Goldhaber-Gordon, David
AU - Kelly, Michael A.
AU - Shen, Zhi Xun
N1 - Funding Information:
We thank Chao-Xing Liu for helpful discussions and A. Budewitz for help in transport characterizations. This work was supported by Defense Advanced Research Projects Agency Microsystems Technology Office, MesoDynamic Architecture Program (MESO) through contract number N66001-11-1-4105. The work at Stanford was also supported by Center for Probing the Nanoscale, an NSF NSEC under grant PHY-0830228 to Z.-X.S. and D.G.-G. to partially support Y.Y., NSF grant DMR1305731 to partially support W.K. and Y.-T.C., the Gordon and Betty Moore Foundation through Grant GBMF3133 and Foundation’s EPiQS Initiative through Grant GBMF4546 to Z.-X.S. to partially support Y.Y. and Y.-T.C., the European Union under the project FP7-PEOPLE-2010-274769 to M.R.C. and the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract DE-AC02-76SF00515 to S.-C.Z. to support J.W. for theoretical calculations and to D.G.-G. for device fabrication and characterization. The work in Würzburg was also supported by the German Research Foundation (DFG grant HA5893/4-1 within SPP 1666 and the Leibniz Program), the EU ERC-AG program (Project 3-TOP) and the Elitenetzwerk Bayern program ‘Topologische Isolatoren’.
Publisher Copyright:
© 2015 Macmillan Publishers Limited.
PY - 2015/5/26
Y1 - 2015/5/26
N2 - 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. This indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.
AB - 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. This indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.
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U2 - 10.1038/ncomms8252
DO - 10.1038/ncomms8252
M3 - Article
C2 - 26006728
AN - SCOPUS:84930224930
SN - 2041-1723
VL - 6
JO - Nature communications
JF - Nature communications
M1 - 7252
ER -