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

Eric Yue Ma; M. Reyes Calvo; Jing Wang; Biao Lian; Mathias Mühlbauer; Christoph Brüne; Yong Tao Cui; Keji Lai; Worasom Kundhikanjana; Yongliang Yang; Matthias Baenninger; Markus König; Christopher Ames; Hartmut Buhmann; Philipp Leubner; Laurens W. Molenkamp; Shou Cheng Zhang; David Goldhaber-Gordon; Michael A. Kelly; Zhi Xun Shen

doi:10.1038/ncomms8252

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

Eric Yue Ma, M. Reyes Calvo, Jing Wang, Biao Lian, Mathias Mühlbauer, Christoph Brüne, Yong Tao Cui, Keji Lai, Worasom Kundhikanjana, Yongliang Yang, Matthias Baenninger, Markus König, Christopher Ames, Hartmut Buhmann, Philipp Leubner, Laurens W. Molenkamp, Shou Cheng Zhang, David Goldhaber-Gordon, Michael A. Kelly, Zhi Xun Shen

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Abstract

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.

Original language	English (US)
Article number	7252
Journal	Nature communications
Volume	6
DOIs	https://doi.org/10.1038/ncomms8252
State	Published - May 26 2015
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physics and Astronomy(all)
Chemistry(all)
Biochemistry, Genetics and Molecular Biology(all)

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10.1038/ncomms8252

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Ma, E. Y., Calvo, M. R., Wang, J., Lian, B., Mühlbauer, M., Brüne, C., Cui, Y. T., Lai, K., Kundhikanjana, W., Yang, Y., Baenninger, M., König, M., Ames, C., Buhmann, H., Leubner, P., Molenkamp, L. W., Zhang, S. C., Goldhaber-Gordon, D., Kelly, M. A., & Shen, Z. X. (2015). Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry. Nature communications, 6, [7252]. https://doi.org/10.1038/ncomms8252

@article{acc963155489467eb849ead050a4ddca,

title = "Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry",

abstract = "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.",

author = "Ma, {Eric Yue} and Calvo, {M. Reyes} and Jing Wang and Biao Lian and Mathias M{\"u}hlbauer and Christoph Br{\"u}ne and Cui, {Yong Tao} and Keji Lai and Worasom Kundhikanjana and Yongliang Yang and Matthias Baenninger and Markus K{\"o}nig and Christopher Ames and Hartmut Buhmann and Philipp Leubner and Molenkamp, {Laurens W.} and Zhang, {Shou Cheng} and David Goldhaber-Gordon and Kelly, {Michael A.} and Shen, {Zhi Xun}",

note = "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{\textquoteright}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 W{\"u}rzburg 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 {\textquoteleft}Topologische Isolatoren{\textquoteright}. Publisher Copyright: {\textcopyright} 2015 Macmillan Publishers Limited.",

year = "2015",

month = may,

day = "26",

doi = "10.1038/ncomms8252",

language = "English (US)",

volume = "6",

journal = "Nature Communications",

issn = "2041-1723",

publisher = "Nature Publishing Group",

}

Ma, EY, Calvo, MR, Wang, J, Lian, B, Mühlbauer, M, Brüne, C, Cui, YT, Lai, K, Kundhikanjana, W, Yang, Y, Baenninger, M, König, M, Ames, C, Buhmann, H, Leubner, P, Molenkamp, LW, Zhang, SC, Goldhaber-Gordon, D, Kelly, MA & Shen, ZX 2015, 'Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry', Nature communications, vol. 6, 7252. https://doi.org/10.1038/ncomms8252

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 -

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

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