SGM 11

Controlling graphene edge state trajectories with a buried gate architecture

Graphene provides a formidable opportunity for the investigation of one-dimensional quantum Hall edge states. Thanks to the fact that electron conduction occurs directly at the surface, a wide range of scanning probe techniques can be used to track the nature and behaviour of electronic states with nanometric precision. We demonstrate the control of edge state trajectories in the quantum Hall regime thanks to a split-gate structure buried under a dielectric layer. Devices were fabricated starting from monocrystalline graphene flakes obtained by chemical vapor deposition. Different n-type and p-type regions can be induced in our devices and used to create a controllable interaction between co-propagating and counter-propagating edge channels at the boundaries of the various quantum Hall regions. We show that the observed resistance values can be understood in terms of edge conduction and mixing relative to three different filling factors in the bulk of the sample, on top of the split-gate, and in the gap between the split-gates. Differently from previous reports, the top surface of graphene is completely accessible and the gating geometry allows an easier electrostatic control of the filling configurations. This offers interesting perspectives for scanning probe investigation of edge channels.

splitgates
Figure 1: (a) Longitudinal resistance (in units of h/e2) measured across a 400-nm-wide QPC as a function of the back-gate (VBG) and split-gate (VSG) voltage biases at B = 10 T. (b) Analytical results using the Landauer-Buttiker formalism reproduce well the observed resistance plateaus.

Publications:

  1. S. Xiang, A. Mrenca-Kolasinska, V. Miseikis, S. Guiducci, K. Kolasinski, C. Coletti, B. Szafran, F. Beltram, S. Roddaro, and S. Heun: Interedge backscattering in buried split-gate-defined graphene quantum point contacts, arXiv:1608.07503 [cond-mat.mes-hall].
  2. S. Xiang, A. Mrenca-Kolasinska, V. Miseikis, S. Guiducci, K. Kolasinski, C. Coletti, B. Szafran, F. Beltram, S. Roddaro, and S. Heun: Interedge backscattering in buried split-gate-defined graphene quantum point contacts, Phys. Rev. B 94, 155446 (2016).
  3. Sedighe Salimian: 2nd place Winner in the Raith Micrograph Award 2018. [Winning Notification] [Raith Calendar 2019] [Communication at NEST]
  4. Sedighe Salimian on the Raith Calendar 2021.

Presented at:

  1. S. Xiang, A. Mrenca-Kolasinska, V. Miseikis, S. Guiducci, K. Kolasinski, C. Coletti, B. Szafran, F. Beltram, S. Roddaro, and S. Heun: Controlling graphene edge-state trajectories with a buried gate architecture, CMD-26, Groningen, The Netherlands, 04 – 09 September 2016 (oral). [Abstract] [Talk]
  2. A. Mreńca-Kolasińska, K. Kolasiński, B. Szafran, S. Xiang, S. Guiducci, F. Beltram, S. Roddaro, V. Miseikis, C. Coletti, and S. Heun: Fractional quantization of quantum Hall longitudinal resistance in n-p-n graphene junctions with split gates, 40th International Conference of Theoretical Physics, Ustroń, Poland, 4 – 9 September 2016 (poster). [Poster]
  3. A. Mreńca-Kolasińska, K. Kolasiński, B. Szafran, S. Xiang, S. Guiducci, F. Beltram, S. Roddaro, V. Miseikis, C. Coletti, and S. Heun: Fractional quantization of longitudinal resistance in split-gate-defined graphene quantum point contact, Workshop on the Ballistic Graphene, Basel, Switzerland, 18 October 2016 (oral). [Talk]
  4. A. Mreńca-Kolasińska, K. Kolasiński, B. Szafran, S. Xiang, S. Guiducci, F. Beltram, S. Roddaro, V. Miseikis, C. Coletti, and S. Heun: Ułamkowa kwantyzacja rezystancji w złączach n-p-n w grafenie, Seminar “Coherence-Correlations-Complexity”, Dept. Of Theoretical Physics, Wrocław University Of Technology, 2 November 2016 (invited seminar). [Abstract] [Talk]
  5. S. Heun: Quantum Hall Effect in a QPC in graphene, Taller Transferencia de Calor a la Nanoescala, UNAM, Mexico-City, Mexico, 14 – 15 November 2016. [Program] [Talk]
  6. S. Xiang, A. Mrenca-Kolasinska, V. Miseikis, S. Guiducci, K. Kolasinski, C. Coletti, B. Szafran, F. Beltram, S. Roddaro, and S. Heun: Inter-edge backscattering in buried split-gate-defined graphene quantum point contacts, Materials.it 2016, Aci Castello, Catania, Italy, 12 – 16 December 2016 (oral). [Abstract] [Talk]
  7. S. Heun: Quantum Hall Effect in Graphene, Universitaet Osnabrueck, Germany (Prof. J. Wollschlaeger), 30 June 2017 (invited). [Abstract] [Talk]