title: Quantum size effect on dielectric function of ultrathin metal film: a first-principles study of Al(1 1 1).
abstract: Using first-principles calculations, we show manifestations of the quantum size effect in the dielectric function ε(2) of free-standing Al(1 1 1) ultrathin films of 1 monolayer to 20 monolayers, taking into account size dependent contributions from both interband and intraband electronic transitions. Overall the in-plane components (interband transition) of ε(2) increase with film thickness at all frequencies, converging towards a constant value. However, the out-of-plane components of ε(2) show a more complex behavior, and, only at frequencies less than 0.75 eV, increase with film thickness without convergence. This suggests that ultrathin films can possibly be used for low-loss plasmonics devices in the visible and ultraviolet range. Our findings may shed light on searching for low-loss plasmonic materials via quantum size effect.
authors.affiliation: Department of Materials Science and Engineering, University of Utah, 201 Presidents Cir, Salt Lake City, UT 84112, USA.
authors.forename: Wenmei
authors.initials: W
authors.lastname: Ming
authors.forename: Steve
authors.initials: S
authors.lastname: Blair
authors.forename: Feng
authors.initials: F
authors.lastname: Liu