Magnetic field dependence of pairing interaction in ferromagnetic superconductors with triplet pairing

TL;DR

This paper presents a microscopic model for triplet superconductivity in ferromagnetic materials, showing how magnetic field orientation influences pairing interactions and critical fields.

Contribution

It introduces a phenomenological spectrum of magnetic fluctuations to describe superconductivity in orthorhombic ferromagnets, differing from the paramagnon model.

Findings

Magnetic field orientation affects the pairing interaction amplitude.

The model explains the anisotropic behavior of the upper critical field.

Field dependence of pairing interaction varies with direction.

Abstract

It is developed a microscopic description of superconductivity in ferromagnetic materials with triplet pairing triggered by the exchange of magnetic fluctuations. Instead widely used paramagnon model we work with phenomenological spectrum of fluctuations in the orthorhombic ferromagnet with strong magnetic anisotropy. Depending of the field orientation parallel or perpendicular to the direction of spontaneous magnetization the effective amplitude of pairing interaction proves to be decreasing or increasing function of magnetic field that allows to explain the drastic difference in magnitudes of upper critical field in these directions.