Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 17: 2D Semiconductors and van der Waals Heterostructures III
HL 17.9: Talk
Tuesday, March 18, 2025, 11:45–12:00, H15
1D graphene superlattices and the influence of the potential shape — •Julia Amann1, Alina Mreńca-Kolasińska2, Angelika Knothe1, Ming-Hao Liu3, Takashi Taniguchi4, Kenji Watanabe4, Dieter Weiss1, and Jonathan Eroms1 — 1University of Regensburg, Germany — 2AGH University, Krakow, Poland — 3National Cheng Kung University, Tainan, Taiwan — 4National Institute for Materials Science, Tsukuba, Japan
One-dimensional superlattices (1DSLs) in graphene have been predicted to exhibit intriguing effects such as transport anisotropy, additional Dirac points and hence higher degeneracy, leading to a different quantum Hall plateau sequence compared to pristine graphene. We use a patterned few-layer graphene gate under an encapsulated monolayer graphene to fabricate a 1DSL device. With the combined effect of a global gate and a patterned bottom gate, we are able to control the superlattice potential strength and carrier density independently. We show low-temperature transport measurements on a gate-tunable 1DSL in monolayer graphene with a period of 50 nm in directions parallel and perpendicular to the modulation using an L-shaped Hall bar. We observe anisotropic transport and the appearance of multiple Dirac points and additional Landau fans in the modulation direction. We also see Weiss oscillations, confirming the 1DSL modulation. However, the predicted anomalous quantum Hall sequence was not observed and we looked more closely at the 1DSL potential we were applying. We found an asymmetric potential shape, which strongly influences the change in the band structure and degeneracy.
Keywords: graphene; superlattice; weiss oscillations; quantum hall; hBN