Phase diagram of UPt$_3$ in the $E_{1g}$ model

TL;DR

This paper demonstrates that the $E_{1g}$ singlet pairing model can accurately describe the phase diagram and anisotropic properties of UPt$_3$, resolving previous conflicts with experimental data.

Contribution

It shows that the $E_{1g}$ model is consistent with experimental phase diagrams and anisotropy, challenging the belief that UPt$_3$ must have triplet pairing.

Findings

The $E_{1g}$ model matches the experimental phase diagram under magnetic fields.

The model explains the anisotropy in the upper critical field curves.

The singlet pairing hypothesis is viable for UPt$_3$.

Abstract

The phase diagram of the unconventional superconductor UPt$_3$ is explained under the long-standing hypothesis that the pair wavefunction belongs to the $E_{1g}$ representation of the point group. The main objection to this theory has been that it disagrees with the experimental phase diagram when a field is applied along the c-axis. By a careful analysis of the free energy this objection is shown to be incorrect. This singlet theory also explains the unusual anisotropy in the upper critical field curves, often thought to indicate a triplet pair function.