Conductance fluctuations and field asymmetry of rectification in graphene

TL;DR

This study explores conductance fluctuations and rectification asymmetry in graphene, revealing how these phenomena vary with carrier density, magnetic field, and electron interactions, highlighting differences between monolayer and bilayer graphene.

Contribution

It provides a detailed analysis of conductance fluctuation behavior and rectification asymmetry in graphene, emphasizing the dependence on carrier density and magnetic field, and the role of electron-electron interactions.

Findings

Conductance fluctuations' correlation energy and field vary differently with carrier density.

Field-dependent fluctuations are nearly independent of carrier density.

Second order conductance fluctuations decay with conductance, consistent with diffusive systems.

Abstract

We investigate conductance fluctuations as a function of carrier density $n$ and magnetic field in diffusive mesoscopic samples made from monolayer and bilayer graphene. We show that the fluctuations' correlation energy and field, which are functions of the diffusion coefficient, have fundamentally different variations with $n$, illustrating the contrast between massive and massless carriers. The field dependent fluctuations are nearly independent of $n$, but the $n$-dependent fluctuations are not universal and are largest at the charge neutrality point. We also measure the second order conductance fluctuations (mesoscopic rectification). Its field asymmetry, due to electron-electron interaction, decays with conductance, as predicted for diffusive systems.