Electron trajectories and magnetotransport in nanopatterned graphene under commensurability conditions

Stephen R. Power, Morten Rishøj Thomsen, Antti-Pekka Jauho, and Thomas Garm Pedersen
Phys. Rev. B 96, 075425 – Published 18 August 2017

Abstract

Commensurability oscillations in the magnetotransport of periodically patterned systems, emerging from the interplay of cyclotron orbit and pattern periodicity, are a benchmark of mesoscopic physics in electron gas systems. Exploiting similar effects in two-dimensional materials would allow exceptional control of electron behavior, but it is hindered by the requirement to maintain ballistic transport over large length scales. Recent experiments have overcome this obstacle and observed distinct magnetoresistance commensurability peaks for perforated graphene sheets (antidot lattices). Interpreting the exact mechanisms behind these peaks is of key importance, particularly in graphene, where a range of regimes are accessible by varying the electron density. In this work, a fully atomistic, device-based simulation of magnetoresistance experiments allows us to analyze both the resistance peaks and the current flow at commensurability conditions. Magnetoresistance spectra are found in excellent agreement with experiment, but we show that a semiclassical analysis, in terms of simple skipping or pinned orbits, is insufficient to fully describe the corresponding electron trajectories. Instead, a generalized mechanism in terms of states bound to individual antidots, or to groups of antidots, is required. Commensurability features are shown to arise when scattering between such states is enhanced. The emergence and suppression of commensurability peaks is explored for different antidot sizes, magnetic field strengths, and electron densities. The insights gained from our study will guide the design and optimization of future experiments with nanostructured graphene.

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  • Received 29 May 2017

DOI:https://doi.org/10.1103/PhysRevB.96.075425

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Stephen R. Power1,2,3,4,*, Morten Rishøj Thomsen2, Antti-Pekka Jauho1, and Thomas Garm Pedersen2,†

  • 1Center for Nanostructured Graphene (CNG), DTU Nanotech, Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
  • 2Center for Nanostructured Graphene (CNG), Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg East, Denmark
  • 3Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Cerdanyola del Vallès), Spain
  • 4Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain

  • *stephen.power@icn2.cat
  • tgp@nano.aau.dk

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Issue

Vol. 96, Iss. 7 — 15 August 2017

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