Conductance quantization in mesoscopic graphene

TL;DR

This paper investigates conductance quantization in mesoscopic graphene with different edge types, revealing distinct quantization behaviors and effects of external conditions like bias, temperature, and magnetic field.

Contribution

It provides a generalized Landauer approach to analyze non-linear transport in graphene, highlighting edge-dependent conductance quantization and magnetic field effects.

Findings

Armchair edges show conductance quantized as 4n e^2/h.

Zig-zag edges exhibit conductance quantized as 4(n+1/2) e^2/h.

Magnetic field influences the quantization plateaus differently than in 2D electron gases.

Abstract

Using a generalized Landauer approach we study the non-linear transport in mesoscopic graphene with zig-zag and armchair edges. We find that for clean systems, the low-bias low-temperature conductance, G, of an armchair edge system in quantized as G/t=4 n e^2/h, whereas for a zig-zag edge the quantization changes to G/t t=4(n+1/2)e^2/h, where t is the transmission probability and n is an integer. We also study the effects of a non-zero bias, temperature, and magnetic field on the conductance. The magnetic field dependence of the quantization plateaus in these systems is somewhat different from the one found in the two-dimensional electron gas due to a different Landau level quantization.