Massive thermal fluctuation of massless graphene electrons

TL;DR

This paper reveals that thermal current noise in graphene, unlike typical conductors, depends nonlinearly on temperature due to the collective mass of massless electrons, linking microscopic properties to macroscopic fluctuations.

Contribution

It introduces a novel understanding of thermal noise in graphene, showing its dependence on collective electron mass and unifying it with conventional conductors.

Findings

Thermal current noise in graphene exhibits nonlinear temperature dependence.

The nonlinear behavior is linked to the collective mass of electrons in graphene.

This work unifies the understanding of thermal fluctuations in graphene and traditional conductors.

Abstract

Whereas thermal current noise $\langle I^2 \rangle$ in typical conductors is proportional to temperature $T$, $\langle I^2 \rangle$ in graphene exhibits a nonlinear $T$ dependence due to the massless nature of individual electrons. This unique $\langle I^2 \rangle$ arising from individually massless electrons is intimately linked to the non-zero collective mass of graphene electrons; namely, $\langle I^2 \rangle$ is set by the equipartition theorem applied to the collective mass's kinetic energy, with the nonlinear $T$-dependence arising from the $T$-dependence of the collective mass. This link between thermal fluctuation and collective dynamics unifies $\langle I^2 \rangle$ in graphene and typical conductors, while elucidating the uniqueness of the former at the same time.