Exotic Superconductivity in the Extended Attractive Hubbard Model

TL;DR

This paper demonstrates that the extended attractive Hubbard model on a square lattice can host a variety of exotic superconducting phases, including mixed-symmetry and chiral states, revealed through mean-field calculations without symmetry constraints.

Contribution

The study introduces a comprehensive mean-field approach that uncovers new mixed-symmetry and chiral superconducting phases in the extended attractive Hubbard model.

Findings

Identification of exotic mixed-symmetry superconducting phases

Discovery of a novel $p_x + i p_y$ state

Demonstration of the model's potential to host exotic states

Abstract

We show that the extended attractive Hubbard model on a square lattice hosts a variety of superconducting phases, including exotic mixed-symmetry phases with $d_{x^2-y^2} + {\rm i} [s + d_{x^2+y^2}]$ and $ d_{x^2-y^2} + p_{x}$ symmetries, and a novel $p_x + {\rm i} p_y$ state. The calculations are performed within the mean-field Bogoliubov-deGennes (BdG) framework. The ground states of the BdG Hamiltonian are obtained via a minimization scheme that does not impose symmetry constraints on the superconducting solutions, hence allowing a mixing of $s$-, $p$- and $d$-wave order parameters. Our results show that extended attractive Hubbard model can serve as an effective model for investigating properties of exotic superconducting states.