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.
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Eric Yue
authors.initials: EY
authors.lastname: Ma
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: M Reyes
authors.initials: MR
authors.lastname: Calvo
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Jing
authors.identifier: 0000000246749485
authors.initials: J
authors.lastname: Wang
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Biao
authors.initials: B
authors.lastname: Lian
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Mühlbauer
authors.affiliation: Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Brüne
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Yong-Tao
authors.initials: YT
authors.lastname: Cui
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA [3] Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Keji
authors.initials: K
authors.lastname: Lai
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Worasom
authors.initials: W
authors.lastname: Kundhikanjana
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Baenninger
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: König
authors.affiliation: Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ames
authors.affiliation: Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Buhmann
authors.affiliation: Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Leubner
authors.affiliation: Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, Würzburg D-97074, Germany.
authors.forename: Laurens W
authors.initials: LW
authors.lastname: Molenkamp
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Zhang
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: David
authors.initials: D
authors.lastname: Goldhaber-Gordon
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kelly
authors.affiliation: 1] Geballe Laboratory for Advanced Materials, Stanford University, 476 Lomita Mall, Stanford, California 94305, USA [2] Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305, USA [3] Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
authors.forename: Zhi-Xun
authors.initials: ZX
authors.lastname: Shen