Quantized electron transport through graphene nanoconstrictions

TL;DR

This paper demonstrates quantized conductance in graphene nanoconstrictions, showing ballistic transport and quantum interference effects, with well-defined edges achieved through a specific fabrication process.

Contribution

It introduces a fabrication method for graphene nanoconstrictions with well-defined edges, enabling clear observation of conductance quantization and quantum interference effects.

Findings

Observation of conductance quantization in graphene nanoconstrictions

Confirmation of ballistic transport through experimental and simulation data

Identification of quantum interference effects affecting conductance plateaus

Abstract

We study the quantization of Dirac fermions in lithographically defined graphene nanoconstrictions. We observe quantized conductance in single nanoconstrictions fabricated on top of a thin hexamethyldisilazane layer over a Si/SiO_2 wafer. This nanofabrication method allows us to obtain well defined edges in the nanoconstrictions, thus reducing the effects of edge roughness on the conductance. We prove the occurrence of ballistic transport and identify several size quantization plateaus in the conductance at low temperature. Experimental data and numerical simulations show good agreement, demonstrating that the smoothing of the plateaus is not related to edge roughness but to quantum interference effects.