Fundamental constraints for the mechanism of superconductivity in cuprates

TL;DR

This paper establishes a criterion based on interlayer contribution to superfluid density to evaluate theories of superconductivity in cuprates, challenging models that rely on interlayer pairing.

Contribution

It introduces a new test for layered superconductor theories using superfluid density anisotropy, ruling out interlayer pairing models for cuprates.

Findings

Interlayer pairing models are inconsistent with measured anisotropy ratios.

The criterion effectively distinguishes viable theories from incompatible ones.

Experimental anisotropy measurements are precise and crucial for theory testing.

Abstract

Considerable progress has been made over the last decade in understanding the phenomenological properties of the cuprate high-T$_{c}$ superconductors and in producing well characterized high quality materials. Nevertheless, the pairing mechanism itself remains controversial. We establish a criterion to test theories for layered superconductors relying on a substantial interlayer contribution. The criterion is based on the ratio of the interlayer contribution to the total superfluid density, which is traced back to the inverse squared effective mass anisotropy. The anisotropy can be measured rather accurately by various experimental techniques. It turns out that models relying on interlayer pairing cannot be considered as serious candidates for the mechanism of superconductivity in cuprate superconductors.