High-order fractal states in graphene superlatticesTools 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 Full text not available from this repository.
Official URL: http://www.pnas.org/content/115/20/5135
AbstractGraphene 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.
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