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High-order fractal states in graphene superlattices.

ABSTRACT: 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.

SUBMITTER: Krishna Kumar R

PROVIDER: S-EPMC5960333 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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High-order fractal states in graphene superlattices.

Krishna Kumar R R Mishchenko A A Chen X X Pezzini S S Auton G H GH Ponomarenko L A LA Zeitler U U Eaves L L Fal'ko V I VI Geim A K AK

Proceedings of the National Academy of Sciences of the United States of America 20180430 20

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 den ...[more]

PMID: 29712870

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