Comment on ``London Theory for Superconducting Phase Transitions in External Magnetic Fields: Application to $\text{UPt}_{3}$''

TL;DR

This paper critically examines a previous theoretical prediction about flux lattice structures in UPt3, arguing that the transitions are crossovers rather than true phase transitions, challenging prior conclusions.

Contribution

It refutes the earlier claim of nontrivial flux lattice structures in UPt3, clarifying the nature of phase transitions in the material's superconducting state.

Findings

Transitions are crossovers, not second-order phase transitions.

Previous predictions about flux lattice structures are incorrect.

Most popular models do not support the predicted flux lattice structures.

Abstract

The authors of the Letter PRL 89, 017004 (2002) predict nontrivial flux lattice structures in UPt3 in vicinity of the superconducting transition between the A and B phases for low magnetic fields, an important conclusion for motivating future experiments. We show that the approach and the conclusions of this Letter are wrong. The transitions between the different superconducting phases in the mixed state are pointed out to be rather crossovers than real second-order phase transitions within the most popular theoretical models of a two-component superconducting order parameter for UPt3.