R. Krishna Kumar
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.; Geim, A.K.
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 Article Type||Article|
|Publication Date||May 15, 2018|
|Journal||Proceedings of the National Academy of Sciences|
|Publisher||National Academy of Sciences|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Krishna Kumar, R., Mishchenko, A., Chen, X., Pezzini, S., Auton, G., Ponomarenko, L., …Geim, A. (2018). High-order fractal states in graphene superlattices. Proceedings of the National Academy of Sciences, 115(20), doi:10.1073/pnas.1804572115|
|Keywords||Graphene; Superlattice; Hofstadter butterfly|
|Copyright Statement||Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf|
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf
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