Comment on "Domain Structure in a Superconducting Ferromagnet"

TL;DR

This paper clarifies a misconception about the coexistence of domain structures in superconducting ferromagnets, resolving apparent contradictions in previous research by analyzing their interpretations.

Contribution

It provides a critical analysis showing that the supposed contradiction between earlier studies is based on misinterpretation, clarifying the conditions for domain structures in superconducting ferromagnets.

Findings

The contradiction is based on misinterpretation.

Domain structures can exist without contradiction.

Clarifies conditions for equilibrium domain structures.

Abstract

According to Faure and Buzdin [Phys. Rev. Lett. 94, 187202 (2005)], in a superconducting ferromagnet a domain structure with a period small compared with the London penetration depth can arise. They claim that this contradicts to the conclusion of Sonin [Phys. Rev. B, 66, 100504 (2002)] that ferromagnetic domain structure in the Meissner state of a superconducting ferromagnet is absent in equilibrium. This contradiction is imaginary, based on misinterpretation of the results of these two papers.