Peculiarities of length scales in a two-orbital superconductor

TL;DR

This paper investigates the spatial characteristics of coherence and magnetic fields in a two-orbital superconductor, revealing critical and non-critical length scales through numerical analysis of a model with intra- and inter-orbital interactions.

Contribution

It introduces a detailed analysis of length scales in a two-orbital superconductor using the negative-U Hubbard model with numerical results for a 2D lattice.

Findings

Identification of critical and non-critical coherence lengths.

Dependence of length scales on hopping integrals and interaction strengths.

Numerical results for a two-dimensional square lattice.

Abstract

We study the spatial behaviour of coherency and magnetic field in a two-orbital superconductor. The superconducting phase transition is caused here by the on-site intra-orbital attractions (negative-U Hubbard model) and inter-orbital pair-transfer interaction. We find the critical (diverging at $T_{c}$) and non-critical (remaining finite) coherence lengths and magnetic field penetration depth for various values of hopping integrals and the strengths of intra-orbital attractions. Numerical results have been obtained for a two-dimensional square lattice.