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Capacitance spectroscopy of the Hofstadter butterfly

 

In a large international collaboration led by Dr Artem Mishchenko and Prof Andre Geim from The University of Manchester, researchers in LNCMI-Grenoble have employed high-sensitivity capacitance measurements under magnetic fields as high as 30 T to probe the physics of the recently discovered “Hofstadter butterfly” in Graphene-BN superlattices.

Graphene capacitance as a function of the magnetic field B and the gate voltage Vb used to tune the carrier density around the Dirac point (Vb=0). This images the density of electronic states (gaps appear as dark stripes) in the "Hofstadter Butterfly" regime.

 

More information :
http://phys.org/news/2014-06-graphene-multi-colored-butterflies.html
 

Related publication : ’Hierarchy of Hofstadter states and replica quantum Hall ferromagnetism in graphene superlattices’ by G. L. Yu, R. V. Gorbachev, J. S. Tu, A. V. Kretinin, Y. Cao, R. Jalil, F.Withers, L. A. Ponomarenko, B. A. Piot, M. Potemski, D. C. Elias, X. Chen, K.Watanabe, T. Taniguchi, I. V. Grigorieva, K. S. Novoselov, V. I. Fal’ko, A. K. Geim and A. Mishchenko, Nature Physics, 2014. DOI : 10.1038/nphys2979