The effects of dielectric disorder on van der Waals interactions in slab geometries

TL;DR

This paper investigates how dielectric disorder influences the thermal Casimir effect between layered slabs, revealing a transition from random to self-averaging behavior as the distance varies, with implications for material design.

Contribution

It introduces a comprehensive analysis of dielectric disorder effects on van der Waals interactions, combining perturbation theory and numerical simulations for the first time.

Findings

Long-distance interactions are self-averaging and depend on an effective dielectric tensor.

Short-distance interactions are sample-dependent and dominated by local dielectric constants.

Numerical simulations confirm theoretical predictions across various disorder distributions.

Abstract

We study the thermal Casimir effect between two thick slabs composed of plane-parallel layers of random dielectric materials interacting across an intervening homogeneous dielectric. It is found that the effective interaction at long distances is self averaging and its value is given by a that between non-random media with the effective dielectric tensor of the corresponding random media. The behavior at short distances becomes random (sample dependent) and is dominated by the local values of the dielectric constants proximal to each other across the homogeneous slab. These results are extended to the regime of intermediate slab separations by using perturbation theory for weak disorder and also by extensive numerical simulations for a number of systems where the dielectric function has a log-normal distribution.