Phenomenological description of anisotropy effects in some ferromagnetic superconductors

TL;DR

This paper phenomenologically analyzes how anisotropy influences ferromagnetic superconductors UGe2, URhGe, and UCoGe, emphasizing uniaxial magnetization anisotropy's dominant role near the Curie temperature.

Contribution

It provides a phenomenological Landau free energy framework to understand anisotropy effects in specific ferromagnetic superconductors, especially UGe2.

Findings

Uniaxial anisotropy of magnetization is the primary influence.

Anisotropy of Cooper pairs and crystal structure have minor effects.

The approach's limitations are discussed.

Abstract

We study phenomenologically by using the previously derived Landau free energy, the role of anisotropy in ferromagnetic superconductors UGe2, URhGe, and UCoGe. The three compounds are separately discussed with the special stress on UGe2. The main effect comes from the strong uniaxial anisotropy of magnetization while the anisotropy of Cooper pairs and crystal anisotropy only slightly change the phase diagram in the vicinity of Curie temperature. The limitations of this approach are also discussed.