High-order fractal states in graphene superlattices

Krishna Kumar, R., Mishchenko, A., Chen, X., Pezzini, S., Auton, G.H., Ponomarenko, L.A., Zeitler, U., Eaves, Laurence, Fal’ko, V.I. and Geim, A.K. (2018) High-order fractal states in graphene superlattices. Proceedings of the National Academy of Sciences, 115 (20). pp. 5135-5139. ISSN 1091-6490

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Graphene superlattices were shown to exhibit high-temperature quantum oscillations due to periodic emergence of delocalized Bloch states in high magnetic fields such that unit fractions of the flux quantum pierce a superlattice unit cell. Under these conditions, semiclassical electron trajectories become straight again, similar to the case of zero magnetic field. Here, we report magnetotransport measurements that reveal second-, third-, and fourth-order magnetic Bloch states at high electron densities and temperatures above 100 K. The recurrence of these states creates a fractal pattern intimately related to the origin of Hofstadter butterflies. The hierarchy of the fractal states is determined by the width of magnetic minibands, in qualitative agreement with our band-structure calculations.

Item Type: Article
RIS ID: https://nottingham-repository.worktribe.com/output/932755
Keywords: Graphene; Superlattice; Hofstadter butterfly
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: https://doi.org/10.1073/pnas.1804572115
Depositing User: Eprints, Support
Date Deposited: 18 May 2018 08:41
Last Modified: 04 May 2020 19:36
URI: https://eprints.nottingham.ac.uk/id/eprint/51866

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