Dimensionality-induced BCS-BEC crossover in layered superconductors

TL;DR

This paper investigates how reducing interlayer coupling in layered superconductors enhances the separation between pair formation and condensation temperatures, leading to a dimensionality-induced BCS-BEC crossover supported by pseudogap observations.

Contribution

It introduces a model showing that decreasing interlayer hopping induces a BCS-BEC crossover in layered superconductors, highlighting the role of dimensionality in superconducting properties.

Findings

Separation of pair-condensation and pair-formation temperatures increases with reduced interlayer hopping.

Dimensionality change can induce a BCS-BEC crossover in layered superconductors.

Pseudogap emergence supports the crossover mechanism.

Abstract

Based on a simple model of a layered superconductor with strong attractive interaction, we find that the separation of the pair-condensation temperature from the pair-formation temperature becomes more remarkable as the interlayer hopping gets smaller. We propose from this result the BCS-BEC crossover induced by the change in dimensionality, for instance, due to insertion of additional insulating layers or application of uniaxial pressure. The emergence of a pseudogap in the electronic density of states, which supports the idea of the dimensionality-induced BCS-BEC crossover, is also verified.