Extended Drude model with memory function for the optical response of disordered conductors
Phys. Rev. B 113, 035139 – Published 21 January, 2026
DOI: https://doi.org/10.1103/mwvq-859y
Abstract
In this work we present an extended Drude model based on a memory function formalism to describe the optical conductivity and permittivity of disordered conductors, spanning non-Fermi liquids to materials featuring complex ion dynamics. The general form of our memory function ensures Kramers-Kronig consistency, and includes transverse optical-longitudinal optical terms that capture diffusive relaxation processes in the material. We validate our extended Drude model by measuring the optical properties of liquid mercury over a wide spectral range spanning the visible to long-wave infrared (wavelengths between 430 nm and ) via spectroscopic ellipsometry. We then demonstrate the versatility of the model for covering diverse regimes of disorder by replicating reported experimental data for the ionic liquid PeMeIm-, the high- superconductor , and thin-film indium tin oxide.
