On the Casimir Effect in the High Tc Cuprates

TL;DR

This paper estimates whether the change in Casimir energy when Cu-O planes in high-Tc cuprates become superconducting could significantly contribute to their condensation energy, suggesting a possible link between quantum vacuum effects and superconductivity.

Contribution

It provides an order of magnitude estimate of the Casimir energy's role in high-Tc cuprates, modeling the system as parallel plasma sheets and highlighting the potential impact of surface plasmons.

Findings

Casimir energy is comparable to the superconducting condensation energy.

The model suggests a van der Waals-like Casimir effect dominated by TM surface plasmons.

Order of magnitude estimate supports possible quantum vacuum contribution to superconductivity.

Abstract

High temperature superconductors have in common that they consist of parallel planes of copper oxide separated by layers whose composition can vary. Being ceramics, the cuprate superconductors are poor conductors above the transition temperature, T_c. Below T_c, the parallel Cu-O planes in those materials become superconducting while the layers in between stay poor conductors. Here, we ask to what extent the change in the Casimir energy that arises when the parallel Cu-O layers become superconducting could contribute to the superconducting condensation energy. Our aim here is merely to obtain an order of magnitude estimate. To this end, the material is modelled as consisting below T_c of parallel plasma sheets separated by vacuum and as without a significant Casimir effect above T_c. Due to the close proximity of the Cu-O planes the system is in the regime where the Casimir effect becomes a van der Waals type effect, dominated by contributions from TM surface plasmons propagating along the ab planes. Within this model, the Casimir energy is found to be of the same order of magnitude as the superconducting condensation energy.