Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 27: Two-dimensional Materials III (joint session HL/CPP)

HL 27.4: Vortrag

Mittwoch, 3. April 2019, 10:15–10:30, H36

Tunable 2D superlattices in graphene — •Robin Huber1, Martin Drienovsky1, Andreas Sandner1, Kenji Watanabe2, Takashi Taniguchi2, Dieter Weiss1, and Jonathan Eroms11Institue of Experimental and Applied Physics, University of Regensburg, Germany — 2National Institute for Materials Science, Tsukuba, Japan

One fascinating way to study the effect of superlattices on graphene are graphene/hBN heterostructures in which moiré superlattices with lattice periods of about 10 nm can be created. These systems made it possible to observe e.g. the famous Hofstadter butterfly in all its beauty. Here we present an alternative method to induce tunable superlattice effects in graphene by the combined action of a global silicon backgate and a patterned bottom gate made from few layer graphene using standard e-beam lithography techniques. We show low temperature transport measurements on an artificially fabricated and gate tunable 2D superlattice in graphene with a lattice period of 40 nm. By switching on a 2D periodic charge carrier density modulation additional Dirac peaks can be observed which are the source of additional Landau fans in magnetotransport. Due to the interplay between the lateral 2D superlattice and a magnetic field, features of the Hofstadter butterfly energy spectrum can be resolved. In addition we show magnetotransport data at an elevated temperature of 120 K where Landau quantization vanishes but Brown-Zak oscillations, which are caused by the 2D periodic potential, are still visible.

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DPG-Physik > DPG-Verhandlungen > 2019 > Regensburg