Fluctuation-induced giant magnetoresistance in charge-neutral graphene

TL;DR

This paper develops a quantitative theory showing that charge density fluctuations in charge-neutral graphene induce a fluctuation conductivity, leading to giant magnetoresistance effects that are highly sensitive to magnetic fields.

Contribution

It introduces a new theoretical framework for fluctuation-induced conductivity in graphene, revealing how charge fluctuations cause giant magnetoresistance.

Findings

Fluctuation conductivity diverges logarithmically with system size at zero magnetic field.

Magnetoresistance is significantly enhanced and rapidly suppressed by small magnetic fields.

The theory quantitatively explains the fluctuation-induced giant magnetoresistance in charge-neutral graphene.

Abstract

The Johnson-Nyquist noise associated with the intrinsic conductivity of the electron liquid, induces fluctuations of the electron density in charge-neutral graphene devices. In the presence of external electric and magnetic fields, the fluctuations of charge density and electric current induce a fluctuating hydrodynamic flow. We show that the resulting advection of charge produces a fluctuation contribution to the macroscopic conductivity of the system, $\sigma_{\mathrm{fl}}$, and develop a quantitative theory of $\sigma_{\mathrm{fl}}$. At zero magnetic field, $\sigma_{\mathrm{fl}}$ diverges logarithmically with the system size and becomes rapidly suppressed at relatively small fields. This results in giant magnetoresistance of the system.