Large temperature dependence of the Casimir force at the metal-insulator transition

TL;DR

This paper develops a universal theory for the Casimir force in poor metals and predicts a significant temperature-dependent change in force during the metal-insulator transition.

Contribution

It introduces a general theoretical framework for the Casimir force in low-conducting materials, including inhomogeneous composites, highlighting temperature effects during phase transitions.

Findings

Large temperature dependence of the Casimir force at the metal-insulator transition.

Universal equations describe the force for various poor metals.

Abrupt changes in the Casimir force occur during phase coexistence.

Abstract

The dependence of the Casimir force on material properties is important for both future applications and to gain further insight on its fundamental aspects. Here we derive a general theory of the Casimir force for low-conducting compounds, or poor metals. For distances in the micrometer range, a large variety of such materials is described by universal equations containing a few parameters: the effective plasma frequency, dissipation rate of the free carriers, and electric permittivity in the infrared range. This theory can also describe inhomogeneous composite materials containing small regions with different conductivity. The Casimir force for mechanical systems involving samples made with compounds that have a metal-insulator transition shows an abrupt large temperature dependence of the Casimir force within the transition region, where metallic and dielectric phases coexist.