Mobilities and Scattering Times in Decoupled Graphene Monolayers

TL;DR

This study investigates the electronic properties of decoupled graphene monolayers formed by folding, revealing differences in mobility and scattering times between layers and analyzing temperature-dependent quantum oscillations.

Contribution

It introduces a method to determine individual layer mobilities in a double-layer graphene system and compares their electronic properties.

Findings

Top layer has higher mobility than bottom layer.

Transport and quantum scattering times are larger in the top layer.

Effective masses and Fermi velocities are reduced in the folded system.

Abstract

Folded single layer graphene forms a system of two decoupled monolayers being only a few Angstroms apart. Using magnetotransport measurements we investigate the electronic properties of the two layers conducting in parallel. We show a method to obtain the mobilities for the individual layers despite them being jointly contacted. The mobilities in the upper layer are significantly larger than in the bottom one indicating weaker substrate influence. This is confirmed by larger transport and quantum scattering times in the top layer. Analyzing the temperature dependence of the Shubnikov-de Haas oscillations effective masses and corresponding Fermi velocities are obtained yielding reduced values down to 66 percent in comparison to monolayers.