Coexistence of triplet superconductivity and itinerant ferromagnetism

TL;DR

This paper explores the coexistence and interplay of triplet superconductivity and itinerant ferromagnetism in uranium-based compounds, analyzing phase diagrams, symmetry, order parameters, and Josephson coupling.

Contribution

It provides a detailed theoretical analysis of the symmetry, order parameters, and domain interactions in ferromagnetic superconductors like UGe2, URhGe, and UCoGe.

Findings

Superconductivity coexists with ferromagnetism in these materials.

The phase diagram features intersecting critical lines for ferromagnetism and superconductivity.

Multidomain states and Josephson coupling are characterized.

Abstract

The triplet superconductivity in $UGe_2$ and $URhGe$ coexists with itinerant ferromagnetism such that in the pressure-temperature phase diagram the whole region occupied by the superconducting state is situated inside a more vast ferromagnetic region. In the same family metal UCoGe the pressure dependent critical lines T_{Curie}(P) and T_{sc}(P) of the ferromagnet and the superconducting phase transitions intersect each other. The two-band multidomain superconducting ferromagnet state arises at temperatures below both of these lines. Here I describe the symmetry and the order parameters of the paramagnet as well of the multidomain ferromagnet superconducting states. The Josephson coupling between two adjacent ferromagnet superconducting domains is discussed.