Problems and paradoxes of the Lifshitz theory

TL;DR

This paper reviews the issues and paradoxes in applying Lifshitz theory to real materials, highlighting that neglecting drift and diffusion currents aligns better with thermodynamics and experiments.

Contribution

It demonstrates that including conduction electron drift and diffusion currents causes contradictions, and supports a simplified Lifshitz model neglecting these effects as more consistent.

Findings

Including drift current contradicts thermodynamics and experiments.

Screening and diffusion effects lead to thermodynamic inconsistencies.

Neglecting conduction currents aligns theory with experimental data.

Abstract

The problems and paradoxes of the Lifshitz theory in application to real dielectric and semiconductor materials are reviewed. It is shown that the inclusion of drift current of conduction electrons into the model of dielectric response results in contradictions with both thermodynamics and experimental data of different experimental groups. Physical reasons why the problems and paradoxes arise are analyzed and found to be connected with the violation of basic applicability condition of the Lifshitz theory, the thermal equilibrium. A recent alternative approach to the resolution of the problems based on the inclusion of screening effects and diffusion current is considered and demonstrated to be thermodynamically and experimentally inconsistent. It is argued that the inclusion of the diffusion current leads to an even deeper violation of thermal equilibrium. Phenomenologically, the Lifshitz theory with role of drift and diffusion currents neglected is shown to be free of problems and in agreement with both thermodynamics and all available experimental data.