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The Hofstadter butterfly in graphene

  • 2/12/2014, Benjamin Piot (LNCMI, Grenoble)

The Hofstadter butterfly in graphene

In this talk, I will describe the recent experimental observation of the “Hofstadter butterfly”, a fractal energy spectrum of Bloch electrons in a magnetic field, in graphene / Boron Nitride (BN) superlattices. I will first introduce the “Hofstadter regime”, where electrons are submitted to a periodic potential and a magnetic field of comparable characteristic lengthscales, and present the concept of its realization in crystallographically aligned graphene-on-BN [1]. I will then discuss the transport experiments we used to probe the “butterfly”, as well as more recent capacitance measurements [2] giving a direct access to the electronic density of states up to magnetic fields of 30T.
 

[1] L.A. Ponomarenko et al, Nature 497, 594–597 (2013)

[2] G.L. Yu et al, Nature Physics 10, 525–529 (2014)