@article{MaCalvoWangetal.2015,
  author    = {Ma, Eric Yue and Calvo, M. Reyes and Wang, Jing and Lian, Biao and M{\"u}hlbauer, Mathias and Br{\"u}ne, Christoph and Cui, Yong-Tao and Lai, Keji and Kundhikanjana, Worasom and Yang, Yongliang and Baenninger, Matthias and K{\"o}nig, Markus and Ames, Christopher and Buhmann, Hartmut and Leubner, Philipp and Molenkamp, Laurens W. and Zhang, Shou-Cheng and Goldhaber-Gordon, David and Kelly, Michael A. and Shen, Zhi-Xun},
  title     = {Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry},
  series = {Nature Communications},
  volume    = {6},
  journal   = {Nature Communications},
  number    = {7252},
  doi       = {10.1038/ncomms8252},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143185},
  year      = {2015},
  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 noninverted 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.},
  language  = {en}
}
@article{KoenigBaenningerGarciaetal.2013,
  author    = {K{\"o}nig, Markus and Baenninger, Matthias and Garcia, Andrei G. F. and Harjee, Nahid and Pruitt, Beth L. and Ames, C. and Leubner, Philipp and Br{\"u}ne, Christoph and Buhmann, Hartmut and Molenkamp, Laurens W. and Goldhaber-Gordon, David},
  title     = {Spatially Resolved Study of Backscattering in the Quantum Spin Hall State},
  series = {Physical Review X},
  volume    = {3},
  journal   = {Physical Review X},
  number    = {2},
  issn      = {2160-3308},
  doi       = {10.1103/PhysRevX.3.021003},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-127225},
  pages     = {21003},
  year      = {2013},
  abstract  = {The discovery of the quantum spin Hall (QSH) state, and topological insulators in general, has sparked strong experimental efforts. Transport studies of the quantum spin Hall state have confirmed the presence of edge states, showed ballistic edge transport in micron-sized samples, and demonstrated the spin polarization of the helical edge states. While these experiments have confirmed the broad theoretical model, the properties of the QSH edge states have not yet been investigated on a local scale. Using scanning gate microscopy to perturb the QSH edge states on a submicron scale, we identify well-localized scattering sites which likely limit the expected nondissipative transport in the helical edge channels. In the micron-sized regions between the scattering sites, the edge states appear to propagate unperturbed, as expected for an ideal QSH system, and are found to be robust against weak induced potential fluctuations.},
  language  = {en}
}