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.
journal_name
Proc Natl Acad Sci U S Aauthors
Krishna Kumar R,Mishchenko A,Chen X,Pezzini S,Auton GH,Ponomarenko LA,Zeitler U,Eaves L,Fal'ko VI,Geim AKdoi
10.1073/pnas.1804572115subject
Has Abstractpub_date
2018-05-15 00:00:00pages
5135-5139issue
20eissn
0027-8424issn
1091-6490pii
1804572115journal_volume
115pub_type
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