Capacitance of Graphene Bilayer as a Which-Layer Probe

TL;DR

This paper demonstrates how capacitance measurements in bilayer graphene can be used to probe layer-specific properties and determine layer polarization, providing insights into broken symmetry states.

Contribution

It offers a detailed theoretical analysis of the near-layer capacitance enhancement effect and introduces capacitance as a tool for studying layer polarization in graphene.

Findings

Capacitance measurements can distinguish layer-specific properties in bilayer graphene.

Theoretical description of the near-layer capacitance enhancement effect.

Capacitance can determine equilibrium layer polarization in graphene.

Abstract

The unique capabilities of capacitance measurements in bilayer graphene enable probing of layer-specific properties that are normally out of reach in transport measurements. Furthermore, capacitance measurements in the top-gate and penetration field geometries are sensitive to different physical quantities: the penetration field capacitance probes the two layers equally, whereas the top gate capacitance preferentially samples the near layer, resulting in the "near-layer capacitance enhancement" effect observed in recent top-gate capacitance measurements. We present a detailed theoretical description of this effect and show that capacitance can be used to determine the equilibrium layer polarization, a potentially useful tool in the study of broken symmetry states in graphene.