Mode-selective cloaking and phase-matching cavity resonances in bilayer graphene transport

TL;DR

This paper investigates phase-matching cavity resonances in bilayer graphene, revealing how internal modes enable perfect electron transmission at specific energies through electrostatic barriers.

Contribution

It introduces a full four-band analysis of mode-resolved transport, identifying phase-matching cavity effects that control tunneling and resonance phenomena in bilayer graphene.

Findings

Perfect transmission occurs at discrete energies due to phase matching of internal modes.

Analytical expressions for transmission and resonance conditions are derived for various barrier geometries.

Internal phase coherence leads to resonance effects that coexist with Fabry-Perot resonances.

Abstract

We study ballistic electron transport through electrostatic barriers in AB-stacked bilayer graphene within a full four-band framework. A mode-resolved analysis reveals how propagating and evanescent channels couple across electrostatic interfaces and how channel selectivity governs transport at normal incidence. We show that perfect transmission can occur at discrete energies due to phase matching of a single internal mode within an individual barrier, without activating the decoupled channels. This effect is interpreted as a phase-matching cavity, namely, an effective cavity formed by internal phase coherence inside the barrier, which yields perfect transmission at discrete energies without true bound states and without opening additional transport channels. For single- and double-barrier geometries, we derive compact analytical expressions for the transmission and identify the corresponding resonance conditions. Extending the analysis to multibarrier structures using a transfer-matrix approach, we demonstrate how perfect resonances driven by internal phase matching coexist with Fabry-Perot-type resonances arising from interbarrier interference. Our results provide a unified, channel-resolved description of tunneling suppression and resonance-assisted transport in bilayer graphene barrier systems.