Nonequilibrium mesoscopic conductance fluctuations as the origin of 1/f noise in epitaxial graphene

TL;DR

This study explores the origins of 1/f noise in epitaxial graphene, linking it to mesoscopic conductance fluctuations and examining how magnetic fields and nonequilibrium conditions influence noise behavior.

Contribution

The paper develops a theoretical model for nonequilibrium mesoscopic conductance fluctuations in graphene and connects it to experimental 1/f noise measurements under various conditions.

Findings

1/f noise decreases exponentially with temperature below 50 K.

Nonequilibrium conditions due to current heating alter noise dependence.

Noise increases in the quantum Hall regime and vanishes at quantized Hall resistance.

Abstract

We investigate the 1/f noise properties of epitaxial graphene devices at low temperatures as a function of temperature, current and magnetic flux density. At low currents, an exponential decay of the 1/f noise power spectral density with increasing temperature is observed that indicates mesoscopic conductance fluctuations as the origin of 1/f noise at temperatures below 50 K. At higher currents, deviations from the typical quadratic current dependence and the exponential temperature dependence occur as a result of nonequilibrium conditions due to current heating. By applying the theory of Kubakaddi [S. S. Kubakaddi, Phys. Rev. B 79, 075417 (2009)], a model describing the 1/f noise power spectral density of nonequilibrium mesoscopic conductance fluctuations in epitaxial graphene is developed and used to determine the energy loss rate per carrier. In the regime of Shubnikov-de Haas oscillations a strong increase of 1/f noise is observed, which we attribute to an additional conductance fluctuation mechanism due to localized states in quantizing magnetic fields. When the device enters the regime of quantized Hall resistance, the 1/f noise vanishes. It reappears if the current is increased and the quantum Hall breakdown sets in.