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HL: Fachverband Halbleiterphysik
HL 80: Quantum transport and quantum Hall effects
HL 80.4: Vortrag
Freitag, 20. März 2020, 10:15–10:30, POT 51
Helical quantum Hall phase in graphene on SrTiO3 — •Louis Veyrat1,7, Corentin Deprez1, Alexis Coissard1, Xiaoxi Li2,3,4, Frédéric Gay1, Kenji Watanbe5, Takashi Taniguchi5, Zheng Vitto Han2,3,4, Benjamin Piot6, Hermann Sellier1, and Benjamin Sacépé1 — 1Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, France — 2SYNL, Chinese Academy of Sciences, P.R. China — 3SMSE, University of Science and Technology of China, P.R. China — 4State Key Laboratory of Quantum Optics and Quantum Optics Devices, SXU, P.R. China — 5NIMS, Tsukuba, Japan — 6LNCMI-CNRS-UGA-UPS-INSA-EMFL, Grenoble, France — 7Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Univ. Würzburg, Germany
The ground state of charge neutral graphene under perpendicular magnetic field was predicted to be a quantum Hall topological insulator with a ferromagnetic order and spin-filtered, helical edge channels. In most experiments, however, an otherwise insulating state is observed and is accounted for by lattice-scale interactions that promote a broken-symmetry state with gapped bulk and edge excitations. We tuned the ground state of the graphene zeroth Landau level to the topological phase via a suitable screening of the Coulomb interaction with a SrTiO3 high-k dielectric substrate. We observed robust helical edge transport emerging at a magnetic field as low as 1T and withstanding temperatures up to 110K over micron-long distances [1]. This new and versatile graphene platform opens new avenues for spintronics and topological quantum computation. [1] Veyrat et al., arXiv:1907:02299