Magnetoresistance in Single Layer Graphene: Weak Localization and Universal Conductance Fluctuation Studies

TL;DR

This study investigates magnetoresistance in single-layer graphene at very low temperature, revealing how weak localization and conductance fluctuations depend on carrier density and phase coherence, influenced by electron interactions and scattering effects.

Contribution

It provides new insights into phase coherence loss mechanisms and the impact of trigonal warping and intra-valley scattering in graphene's magnetoresistance behavior.

Findings

Phase coherence decreases with lower carrier density.

Trigonal warping effects are significant at high densities.

Universal conductance fluctuation amplitude diminishes near the Dirac point.

Abstract

We report measurements of magnetoresistance in single-layer graphene as a function of gate voltage (carrier density) at 250 mK. By examining signatures of weak localization (WL) and universal conductance fluctuations (UCF), we find a consistent picture of phase coherence loss due to electron-electron interactions. The gate-dependence of the elastic scattering terms suggests that the effect of trigonal warping, i.e., the non-linearity of the dispersion curves, may be strong at high carrier densities, while intra-valley scattering may dominate close to the Dirac point. In addition, a decrease in UCF amplitude with decreasing carrier density can be explained by a corresponding loss of phase coherence.