Quantum Size Effect on Dielectric Properties of Ultrathin Metallic Film: A First-Principles Study of Al(111)

TL;DR

This study uses first-principles calculations to explore how quantum size effects influence the dielectric properties of ultrathin Al(111) films, revealing size-dependent electronic transitions and potential for low-loss plasmonic applications.

Contribution

It demonstrates the quantum size effect on dielectric functions of Al(111) ultrathin films, highlighting reduced interband transitions in films thinner than 15 monolayers.

Findings

Quantum size effect alters dielectric properties of ultrathin Al(111) films.

Interband transitions are suppressed in films thinner than 15 monolayers.

Potential for low-loss plasmonic applications using ultrathin aluminum films.

Abstract

Quantum manifestations of various properties of metallic thin films by quantum size effect (QSE) have been studied intensively. Here, using first-principles calculations, we show quantum manifestation in dielectric properties of Al(111) ultrathin films. The QSE on the dielectric function is revealed, which arises from size dependent contributions from both intraband and interband electronic transitions. More importantly, the in-plane interband transitions in the films thinner than 15 monolayers are found to be smaller than the bulk counterpart in the energy range from 1.5~eV to 2.5~eV. This indicates less energy loss with plasmonic material of Al in the form of ultrathin film. Our findings may shed light on searching for low-loss plasmonic materials via quantum size effect.