Casimir Interactions for Anisotropic Magnetodielectric Metamaterials

TL;DR

This paper extends Casimir-Lifshitz theory to anisotropic magnetodielectric metamaterials, analyzing forces and the potential to detect magnetic effects, highlighting challenges due to background material properties and dissipation.

Contribution

It generalizes Casimir interactions to anisotropic magnetodielectric media and explores the feasibility of detecting magnetic effects through force measurements.

Findings

Magnetic effects are difficult to detect due to background material contributions.

Engineering of metamaterials can reduce Casimir stiction but faces practical challenges.

Magnetic contributions in dielectric metamaterials are too weak for repulsive Casimir forces.

Abstract

We extend our previous work [Phys. Rev. Lett. {\bf 100}, 183602 (2008)] on the generalization of the Casimir-Lifshitz theory to treat anisotropic magnetodielectric media, focusing on the forces between metals and magnetodielectric metamaterials and on the possibility of inferring magnetic effects by measurements of these forces. We present results for metamaterials including structures with uniaxial and biaxial magnetodielectric anisotropies, as well as for structures with isolated metallic or dielectric properties that we describe in terms of filling factors and a Maxwell Garnett approximation. The elimination or reduction of Casimir "stiction" by appropriate engineering of metallic-based metamaterials, or the indirect detection of magnetic contributions, appear from the examples considered to be very challenging, as small background Drude contributions to the permittivity act to enhance attraction over repulsion, as does magnetic dissipation. In dielectric-based metamaterials the magnetic properties of polaritonic crystals, for instance, appear to be too weak for repulsion to overcome attraction. We also discuss Casimir-Polder experiments, that might provide another possibility for the detection of magnetic effects.