Cryptoferromagnetism in Superconductors with Broken Time-Reversal Symmetry

TL;DR

This paper theoretically investigates cryptoferromagnetic states in superconductors with broken time-reversal symmetry, analyzing phase transitions and magnetic phase diagrams to identify observable signatures of coexistence of superconductivity and ferromagnetism.

Contribution

It introduces a theoretical framework for understanding cryptoferromagnetism in superconductors with intrinsic magnetic order, including phase diagrams and magnetization predictions.

Findings

Cryptoferromagnetic states can coexist with superconductivity.

Magnetization curves reveal signatures of cryptoferromagnetism.

Phase diagrams illustrate transitions between different magnetic states.

Abstract

The cryptoferromagnetic state (the state with intrinsic domain structure) in superconducting ferromagnets subjected to external magnetic field is studied theoretically. Ferromagnetism originates either from electron spin or the intrinsic angular momentum of Cooper pairs (chiral p-wave superconductors like $\mathrm{Sr_2 Ru O_4}$). The phase transitions towards the Meissner and the mixed states are investigated, and the magnetic phase diagrams are obtained. Cryptoferromagnetism, as a form coexistence of superconductivity and ferromagnetism, can be detected by observation of magnetization curves predicted in the present analysis.