Parallel transport and layer-resolved thermodynamic measurements in twisted bilayer graphene

TL;DR

This paper demonstrates a novel method for in situ thermodynamic measurements in twisted bilayer graphene using parallel transport, achieving high mobility and conductivity, and providing insights into layer-specific chemical potentials.

Contribution

It introduces a twist-enabled, contactless method for measuring layer-resolved chemical potentials in bilayer graphene, simplifying thermodynamic studies.

Findings

Achieved ultra-high mobility and conductivity in twisted bilayer graphene.

Validated a simple phenomenology of parallel conduction between layers.

Developed a new in situ measurement technique for chemical potential in layered systems.

Abstract

We employ dual-gated 30{\deg}-twisted bilayer graphene to demonstrate simultaneous ultra-high mobility and conductivity (up to 40 mS at room temperature), unattainable in a single-layer of graphene. We find quantitative agreement with a simple phenomenology of parallel conduction between two pristine graphene sheets, with a gate-controlled carrier distribution. Based on the parallel transport mechanism, we then introduce a method for in situ measurements of the chemical potential of the two layers. This twist-enabled approach, neither requiring a dielectric spacer, nor separate contacting, has the potential to greatly simplify the measurement of thermodynamic quantities in graphene-based systems of high current interest.