The effect of electron dielectric response on the quantum capacitance of graphene in a strong magnetic field

TL;DR

This paper investigates how the dielectric response of graphene influences its quantum capacitance in strong magnetic fields, combining theoretical modeling with experimental measurements to reveal significant effects and agreement.

Contribution

It introduces a theoretical framework and experimental validation for the impact of wave vector-dependent dielectric polarizability on graphene's quantum capacitance in magnetic fields.

Findings

Quantum capacitance can be negative in strong magnetic fields.

Dielectric polarizability significantly affects quantum capacitance.

Theory and experiments show good agreement.

Abstract

The quantum capacitance of graphene can be negative when the graphene is placed in a strong magnetic field, which is a clear experimental signature of positional correlations between electrons. Here we show that the quantum capacitance of graphene is also strongly affected by its dielectric polarizability, which in a magnetic field is wave vector-dependent. We study this effect both theoretically and experimentally. We develop a theory and numerical procedure for accounting for the graphene dielectric response, and we present measurements of the quantum capacitance of high-quality graphene capacitors on boron nitride. Theory and experiment are found to be in good agreement.