Open AccessDivergence of the dielectric constant in ultrathin granular metal films near the percolation threshold
Author(s) -
Hicham Bakkali,
E. Blanco,
S. E. Lofland,
Manuel Domı́nguez
Publication year - 2020
Publication title -
new journal of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.584
H-Index - 190
ISSN - 1367-2630
DOI - 10.1088/1367-2630/aba021
Subject(s) - condensed matter physics , dielectric , physics , percolation threshold , thermal conduction , quantum tunnelling , conductivity , percolation (cognitive psychology) , power law , metal , electrical resistivity and conductivity , materials science , quantum mechanics , statistics , mathematics , neuroscience , metallurgy , biology
We report on the electronic and optical properties of ultrathin granular films. We demonstrate that the static dielectric constant increases with thickness in the dielectric regime and diverges at the critical thickness, as predicted by classical percolation theory. However, for thicker samples, the dc conductivity does not obey scaling laws due to the presence of tunneling conduction. In this region the dielectric constant is positive, and the electronic transport is not metallic but can be described by Jonscher’s universal power law, even though there is a Drude-like response indicating the presence of free charge carriers. Only for thicker films when the dielectric constant becomes negative is there metallic conduction.