Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 3: Graphene: Magnetic Fields (jointly with DS, HL, MA, and TT)

O 3.7: Talk

Monday, March 11, 2013, 11:00–11:15, H17

Splitting of the Zero-Energy Landau Level and Universal Dissipative Conductivity at Critical Points in Graphene — •Frank Ortmann¹ and Stephan Roche^1,2 — ¹Catalan Institute of Nanotechnology, Barcelona (Spain) — ²ICREA, Barcelona (Spain)

In graphene, the interaction of electrons with disorder impacts on their transport signature in a variety of experiments. Magnetotransport experiments can serve as an additional tool to probe this interaction with magnetic fields ranging from the low-field limit of weak antilocalization (∼mT) [1,2] to high fields defining the quantum Hall regime (∼10T). Being under study ever since the discovery of graphene, magnetic fields may unveil some interesting physics hidden otherwise or may generate new effects [3]. We are calculating the Kubo conductivity of graphene σ_xx and σ_xy in the presence of both weak and strong disorder and magnetic fields using a linear scaling method. This allows us to model realistic graphene samples up to micrometer size. Here we present our recent work on charge transport in the quantum-Hall regime and discuss our findings of universal conductivities. Particular emphasize is put on the non-trivial interference of disorder and magnetic-field and results from our novel order-N Hall-transport code.

[1] F.V. Tikhonenko et al. Phys. Rev. Lett. 103, 226801 (2009)

[2] F. Ortmann et al. EPL 94, 47006 (2011)

[3] D.A. Abanin et al. Science 332, 328 (2011)