Size Effects in the Electronic Heat Capacity of Small Platinum Particles Embedded in Silica.

摘要

Heat-capacity measurements on sputtered granular metal films of Pt-SiO2 were carried out between 1 and 12 K. Mean sizes of the Pt particles range from 10 to 26 A; This small size coupled with these low temperatures makes the average electronic-energy-level spacing delta in the Pt metal large compared to kBT. A quantum size effect in the electronic heat capacity of a metal has been predicted in this limit, delta much greater than kBT, and is observed here for the first time, although in a very limited temperature range. Difficulty in observing this size effect was caused by a large heat-capacity enhancement over bulk values in the insulating vitreous silica. This enhancement is ascribed to the Pt particle inclusions in the host SiO2 matrix augmenting the low-frequency Einstein modes first observed in the specific heat of SiO2 by Flubacher et al. (Author)