Edge channels in a graphene Fabry-Perot interferometer

TL;DR

This paper investigates electron transport in graphene Fabry-Pérot interferometers, highlighting how edge structure and confinement methods influence conductance patterns, scattering, and interference visibility.

Contribution

It provides a comparative analysis of nanolithography and electrostatic confinement methods, revealing their effects on edge channel behavior and interference in graphene devices.

Findings

Nanolithography constrictions cause strong inter-channel scattering and non-adiabatic transport.

Electrostatic confinement with a staggered potential results in adiabatic transport.

Interference visibility decreases exponentially with temperature, especially at low temperatures.

Abstract

Quantum-mechanical calculations of electron magnetotransport in graphene Fabry-P\'{e}rot interferometers are presented with a focus on the role of spatial structure of edge channels. For an interferometer that is made by removing carbon atoms, which is typically realized in nanolithography experiments, the constrictions are shown to cause strong inter-channel scattering that establishes local equilibrium and makes the electron transport non-adiabatic. Nevertheless, two-terminal conductance reveals a common Aharonov-Bohm oscillation pattern, independent of crystallographic orientation, which is accompanied by single-particle states that sweep through the Fermi energy for the edge channels circulating along the physical boundary of the device. The interferometer constrictions host the localized states that might shorten the device or disrupt the oscillation pattern. For an interferometer that is created by electrostatic confinement, which is typically done in the split-gate experiments, electron transport is shown to be adiabatic if the staggered potential is introduced additionally into the model. Interference visibility decays exponentially with temperature with a weaker dependence at low temperature.