The Frequency Dependent Conductivity of Electron Glasses
Abstract
Results of DC and frequency dependent conductivity in the quantum limit, i.e. hw > kT, for a broad range of dopant concentrations in nominally uncompensated, crystalline phosphorous doped silicon and amorphous niobium-silicon alloys are reported. These materials fall under the general category of disordered insulating systems, which are referred to as electron glasses. Using microwave resonant cavities and quasi-optical millimeter wave spectroscopy we are able to study the frequency dependent response on the insulating side of the metal-insulator transition. We identify a quantum critical regime, a Fermi glass regime and a Coulomb glass regime. Our phenomenological results lead to a phase diagram description, or taxonomy, of the electrodynamic response of electron glass systems.
Keywords
Cite
@article{arxiv.cond-mat/0303589,
title = {The Frequency Dependent Conductivity of Electron Glasses},
author = {E. Helgren and N. P. Armitage and G. Gruner},
journal= {arXiv preprint arXiv:cond-mat/0303589},
year = {2009}
}