Condensed Matter Seminar

Dmitri Abanine
MIT

Thursday, December 6, 2007
1:00 pm in SPL 52

Quantum Hall Effect in Graphene p-n Junctions

Abstract: In the first part of the talk, I will focus on Quantum Hall Effect (QHE) in graphene p-n junctions, which has been recently demonstrated experimentally. I will explain the observed conductance quantization which is fractional in the bipolar regime and integer in the unipolar regime in terms of QH edge modes propagating along and across the p-n interface. In the bipolar regime the electron and hole modes can mix at the p-n boundary, leading to current partition and quantized shot noise plateaus similar to those of conductance, while in the unipolar regime transport is noiseless. In the second part of the talk, I will discuss unusual nature of ν = 0 QHE state in graphene and show that electron transport in this regime may be dominated by counter-propagating edge states. Such states, intrinsic to massless Dirac quasiparticles, manifest themselves in a large longitudinal resistivity ρ_xx~h/e2, in striking contrast to ρ_xx behavior in the standard QHE.