# Pairing Tendencies in a Two-orbital Hubbard Model in One Dimension

## TL;DR

This study uses DMRG to analyze a one-dimensional two-orbital Hubbard model, revealing hole pairing tendencies at intermediate U and significant Hund coupling, relevant for understanding superconductivity in quasi-1D iron-based materials.

## Contribution

It demonstrates the emergence of hole pairing in a 1D two-orbital Hubbard model at intermediate U and specific Hund coupling, highlighting the role of magnetic correlations.

## Key findings

- Hole binding occurs at intermediate U and Hund coupling J_H/U=0.25.
- Dominant pair correlations involve spin singlet, nearest-neighbor, different orbitals.
- Magnetic moments and antiferromagnetic correlations are crucial for pairing.

## Abstract

The recent discovery of superconductivity under high pressure in the ladder compound BaFe$_2$S$_3$ has opened a new field of research in iron-based superconductors with focus on quasi one-dimensional geometries. In this publication, using the Density Matrix Renormalization Group technique, we study a two-orbital Hubbard model defined in one dimensional chains. Our main result is the presence of hole binding tendencies at intermediate Hubbard $U$ repulsion and robust Hund coupling $J_H/U=0.25$. Binding does not occur neither in weak coupling nor at very strong coupling. The pair-pair correlations that are dominant near half-filling, or of similar strength as the charge and spin correlation channels, involve hole-pair operators that are spin singlets, use nearest-neighbor sites, and employ different orbitals for each hole. The Hund coupling strength, presence of robust magnetic moments, and antiferromagnetic correlations among them are important for the binding tendencies found here.