Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 74: Poster IIIA
HL 74.24: Poster
Thursday, March 19, 2020, 15:00–17:30, P2/2OG
Small angle twisted bilayer graphene — Simon Wagner1, Tobias Rockinger1, Kenji Watanabe2, Takashi Taniguchi2, Dieter Weiss1, and •Jonathan Eroms1 — 1Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany — 2National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
One recent observation in graphene is the appearance of interaction effects in twisted bilayer graphene (TBG) with a twist angle of about 1.1∘, which is called magic angle. Depending on the angle between the two layers the band structure changes and can show flat bands. At the magic angle, the band width is minimal. This leads to enhanced carrier-carrier interaction resulting in both Mott-like insulating behavior and superconductivity. Both effects were recently discovered by Cao et al. in magic angle bilayer graphene. We fabricated TBG by van der Waals stacking of two parts of a single graphene monolayer (the tear and stack-technique), which we encapsulate in hexagonal boron nitride. During fabrication the twist angle is controlled in a dedicated setup and can be verified afterwards by the position of secondary Dirac peaks and flux-dependent features in a Landau fan diagram. In a sample with a twist angle of about 0.9∘, we observe those signatures of a superlattice potential, and also detect additional insulating states at gate voltages corresponding to filling 1, 2 or 3 electrons per moire unit cell.
Y. Cao, et al., Nature 556, 80 (2018), ibid. 43