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

摘要

Quantum manifestations of various properties of metallic thin films byquantum size effect (QSE) have been studied intensively. Here, usingfirst-principles calculations, we show quantum manifestation in dielectricproperties of Al(111) ultrathin films. The QSE on the dielectric function isrevealed, which arises from size dependent contributions from both intrabandand interband electronic transitions. More importantly, the in-plane interbandtransitions in the films thinner than 15 monolayers are found to be smallerthan the bulk counterpart in the energy range from 1.5~eV to 2.5~eV. Thisindicates less energy loss with plasmonic material of Al in the form ofultrathin film. Our findings may shed light on searching for low-loss plasmonicmaterials via quantum size effect.