Photon-assisted transport in bilayer graphene flakes

TL;DR

This paper investigates how a time-dependent gate voltage influences quantum interference and spin-polarized transport in bilayer graphene flakes, revealing tunable antiresonances and potential THz frequency detection applications.

Contribution

It introduces a method to modulate quantum interference effects in bilayer graphene using an ac gate field, enabling control over conductance and spin polarization.

Findings

Oscillating fields can tune or eliminate antiresonances.

Interference patterns depend on ac-field parameters.

System can function as a THz frequency detector.

Abstract

The electronic conductance of graphene-based bilayer flake systems reveal different quantum interference effects, such as Fabry-P\'erot resonances and sharp Fano antiresonances on account of competing electronic paths through the device. These properties may be exploited to obtain spin-polarized currents when the same nanostructure is deposited above a ferromagnetic insulator. Here we study how the spin-dependent conductance is affected when a time-dependent gate potential is applied to the bilayer flake. Following a Tien-Gordon formalism we explore how to modulate the transport properties of such systems via appropriate choices of the $ac$-field gate parameters. The presence of the oscillating field opens the possibility of tuning the original antiresonances for a large set of field parameters. We show that interference patterns can be partially or fully removed by the time-dependent gate voltage. The results are reflected in the corresponding weighted spin polarization which can reach maximum values for a given spin component. We found that differential conductance maps as functions of bias and gate potentials show interference patterns for different $ac$-field parameter configurations. The proposed bilayer graphene flake systems may be used as a frequency detector in the THz range.