Softer than normal, but not as soft as one might think: Spontaneous flux lattices in ferromagnetic spin-triplet superconductors

TL;DR

This paper develops a theory predicting large fluctuations in the spontaneous vortex lattice of ferromagnetic spin-triplet superconductors, suggesting observable experimental signatures distinct from conventional flux lattices.

Contribution

It introduces a theoretical framework for spontaneous flux lattices in ferromagnetic spin-triplet superconductors and predicts their unique fluctuation behavior.

Findings

Predicted huge long-wavelength fluctuations in the spontaneous flux lattice.

Identified experimental signatures for observing the spontaneous flux lattice.

Compared fluctuation behavior with spin-singlet ferromagnetic superconductors.

Abstract

A theory is developed for the spontaneous vortex lattice that is expected to occur in the ferromagnetic superconductors ZrZn_2, UGe_2, and URhGe, where the superconductivity is likely of spin-triplet nature. The long-wavelength fluctuations of this spontaneous flux lattice are predicted to be huge compared to those of a conventional flux lattice, and to be the same as those for spin-singlet ferromagnetic superconductors. It is shown that these fluctuations lead to unambiguous experimental signatures which may provide the easiest way to observe the spontaneous flux lattice.