Coexistence of ferromagnetism and singlet superconductivity via kinetic exchange

TL;DR

This paper introduces a new mechanism where kinetic exchange enables the coexistence of metallic ferromagnetism and singlet superconductivity, highlighting a positive feedback loop that enhances both phenomena.

Contribution

It proposes a novel kinetic exchange-based mechanism for coexistence of ferromagnetism and singlet superconductivity, supported by phase diagram analysis.

Findings

Coexistence is facilitated by positive feedback on kinetic energy gain.

Magnetization and pairing amplitude evolve together in the model.

Phase diagram reveals stable coexistence regions.

Abstract

We propose a novel mechanism for the coexistence of metallic ferromagnetism and singlet superconductivity assuming that the magnetic instability is due to kinetic exchange. Within this scenario, the unpaired electrons which contribute to the magnetization have a positive feedback on the gain of the kinetic energy in the coexisting phase by undressing the effective mass of the carriers involved into the pairing. The evolution of the magnetization and pairing amplitude, and the phase diagram are first analyzed for a generic kinetic exchange model and then are determined within a specific case with spin dependent bond-charge occupation.