Quantum pumping in a ballistic graphene bilayer

TL;DR

This paper studies quantum pumping of Dirac fermions in a clean graphene bilayer, revealing how the pumped current depends on system parameters and comparing it with conductance behavior, with implications for experimental realization.

Contribution

It provides a theoretical analysis of quantum pumping in a ballistic graphene bilayer, highlighting the dependence of pumped current on interlayer coupling and system dimensions, which is a novel insight.

Findings

Pumped current scales linearly with interlayer coupling length for small L/l_{perp}

Maximum pumped current occurs around L/l_{perp} ~ 1

Pumped current exhibits a logarithmic dependence for large L/l_{perp}

Abstract

We investigate quantum pumping of massless Dirac fermions in an ideal (impurity free) double layer of graphene. The pumped current is generated by adiabatic variation of two gate voltages in the contact regions to a weakly doped double graphene sheet. At the Dirac point and for a wide bilayer with width W much larger then length L, we find that the pumped current scales linearly with the interlayer coupling length l_{perp} for L/l_{perp} << 1, is maximal for L/l_{perp} ~ 1, and crosses over to a log(L/l_{perp})/(L/l_{perp})-dependence for L/l_{perp} >> 1. We compare our results with the behavior of the conductance in the same system and discuss their experimental feasibility.