The superconducting phase diagram in a model for tetragonal and cubic systems with strong antiferromagnetic correlations

TL;DR

This paper models the superconducting phase diagram in tetragonal and cubic systems with strong antiferromagnetic correlations, revealing multiple phase transitions and proposing CeIn3 as a candidate for time-reversal symmetry-breaking superconductivity.

Contribution

It introduces a detailed phase diagram analysis using FLEX on the Hubbard model, highlighting the emergence of time-reversal symmetry-breaking states in nearly cubic lattices.

Findings

Two superconducting phase transitions in cubic systems.

Suppression of time-reversal symmetry-breaking phase with tetragonal distortion.

CeIn3 as a candidate for time-reversal symmetry-breaking superconductivity.

Abstract

We calculate the superconducting phase diagram as a function of temperature and z-axis anisotropy in a model for tetragonal and cubic systems having strong antiferromagnetic fluctuations. The formal basis for our calculations is the fluctuation exchange approximation (FLEX) applied to the single-band Hubbard model near half-filling. For nearly cubic lattices, two superconducting phase transitions are observed as a function of temperature with the low-temperature state having the time-reversal symmetry-breaking form, $d_{x^2 - y^2} \pm id_{3z^2 -r^2}$. With increasing tetragonal distortion the time-reversal-symmetry-breaking phase is suppressed giving way to only $d_{x^2 - y^2}$ or $d_{3z^2 -r^2}$ single-component phases. Based on these results, we propose that CeIn$_3$ is a candidate for exhibiting a time-reversal symmetry-breaking superconducting state.