Optimal interlayer hopping and high temperature Bose-Einstein condensation of local pairs in quasi 2D superconductors

TL;DR

This paper investigates how interlayer hopping influences high-temperature Bose-Einstein condensation of local pairs in quasi-2D superconductors, revealing optimal conditions for superconductivity related to their layered structure.

Contribution

It provides analytical and numerical solutions for local pairing in anisotropic lattices, highlighting the role of interlayer hopping in maximizing transition temperatures.

Findings

Optimal interlayer hopping enhances BEC transition temperature.

Quasi-2D structure is crucial for high-temperature superconductivity.

Analytical and numerical methods applied to intermediate and strong V regimes.

Abstract

Both FeSe and cuprate superconductors are quasi 2D materials with high transition temperatures and local fermion pairs. Motivated by such systems, we investigate real space pairing of fermions in an anisotropic lattice model with intersite attraction, V, and strong local Coulomb repulsion, U, leading to a determination of the optimal conditions for superconductivity from Bose-Einstein condensation. Our aim is to gain insight as to why high temperature superconductors tend to be quasi 2D. We make both analytically and numerically exact solutions for two body local pairing applicable to intermediate and strong V. We find that the Bose Einstein condensation temperature of such local pairs is maximal when hopping between layers is intermediate relative to in-plane hopping, indicating that the quasi 2D nature of unconventional superconductors has an important contribution to their high transition temperatures.