Enhanced repulsive Casimir forces between gold and thin magnetodielectric plates

TL;DR

This paper investigates how magnetic and metallic plates can produce repulsive Casimir forces, showing that tuning magnetic properties and thickness enables repulsion at sub-micron distances, with potential experimental applications.

Contribution

It introduces a quantitative analysis of how magnetic properties and thickness of plates influence Casimir repulsion, highlighting conditions for achieving repulsion at nanometer scales.

Findings

Repulsion exists for magnetic plates with erromagnetic permeability and thinness.

Temperature affects the transition between attractive and repulsive forces.

Parameters can be tuned for repulsion at sub-micron separations.

Abstract

We calculate repulsive Casimir forces between metallic and magnetic plates and quantitatively probe the magnetic plate's properties as tuning knobs for the repulsion. Namely, the plate's thickness and its low-frequency permittivity and permeability. For a thin magnetic plate ($\leq 10\,\text{nm}$), we find that repulsion can exist as long as $\mu(0) \geq \epsilon(0)$. We also explore the effect of temperature on the repulsion and transition distance between attractive and repulsive interactions. We show how the parameters can be tuned to allow repulsion at sub-micron separation regimes, making it potentially accessible to known high-resolution measurement techniques using magnetic van der Waals materials.