Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: Transport: Graphene and Carbon Nanotubes
TT 26.9: Vortrag
Mittwoch, 25. März 2009, 16:30–16:45, HSZ 03
Universal conductivity and shot noise in graphene quantum billiards — •Adam Rycerz1,2 and Michael Wimmer1 — 1Institut für Theoretische Physik, Universität Regensburg, D-93040, Germany — 2Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30059 Kraków, Poland
We study the ballistic electron transport through two types of quantum billiards in undoped graphene: a finite section of the Corbino disc, and a long insulating nanoribbon attached to the leads in a way that the current is flowing perpendicularly to the main ribbon axis. We found such a closed and an open billiard behave similarly when changing geometrical parameters. Namely, both billiards show the pseudodiffusive regime, in which the conductance is equal to that of the dissipative medium characterized by the conductivity σ0=4e2/π h, whereas the Fano factor F=1/3. In the opposite tunneling regime, the conductance shows power-law decay with a distance between leads, and the shot-noise is Poissonian (F=1). Additionally, in the crossover region between tunneling and pseudodiffusive regimes, the conductance G≈ (1−F)× 4e2/h, what shows the transport is dominated by a single evanescent mode with the fourfold (spin and valley) degeneracy.