Evidence for a fractional fractal quantum Hall effect in graphene superlattices

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Science  04 Dec 2015:
Vol. 350, Issue 6265, pp. 1231-1234
DOI: 10.1126/science.aad2102

Mixing interactions and superlattices

Under the influence of an external magnetic field, the energies of electrons in two-dimensional systems group into the so-called Landau levels. In the cleanest samples, interactions among electrons lead to fractional quantum Hall (FQH) states. If such a system is then subjected to a superlattice potential, it is unclear whether the fragile FQH states will survive. To address this question, Wang et al. sandwiched graphene between two layers of hexagonal boron nitride. Transport measurements on the superlattice showed that some FQH states did survive. Furthermore, the interplay between interactions and the superlattice potential produced additional, anomalous states.

Science, this issue p. 1231