Quasi-stationary near-gate plasmons in van der Waals heterostructures

TL;DR

This paper develops a theoretical framework for near-gate plasmons in van der Waals heterostructures, revealing gate-size-quantized modes and their experimental signatures as Fano-like resonances, facilitating near-field imaging of these plasmons.

Contribution

It introduces a novel theory describing quasi-stationary near-gate plasmons in van der Waals heterostructures with quantized modes and resonance phenomena.

Findings

Near-gate plasmons form discrete, quantized modes in heterostructures.

These plasmons manifest as Fano-like resonances in scattering spectra.

The theory enables near-field imaging of the plasmon spectrum.

Abstract

Near-gate plasmons are a new type of plasma oscillations emerging in homogeneous two-dimensional electron systems where a gate provides partial screening of electron-electron interaction. Here we develop a theory of the near-gate plasmons in van der Waals heterostructures comprising a conducting layer separated by a thin insulator from an uncharged disk-shaped gate. We show that in these structures the near-gate plasmons form gate-size-quantized quasi-stationary discrete modes even in the collisionless limit. Belonging to continuum spectrum of two-dimensional plasmons outside of the disk-gate, the near-gate plasmons are manifested as Fano-like resonances in frequency and magnetodispersions of scattering cross-section of the former scattered off the region under the gate. This enables to recover spectrum of the near-gate plasmons in the van der Waals heterostructures using near-field imaging techniques.