Ferromagnetism in neutron and charge neutral beta-equilibrated nuclear matter

TL;DR

This paper investigates the possibility of ferromagnetism in dense neutron and nuclear matter using a baryon-meson interaction model, revealing conditions under which strong magnetic fields could emerge.

Contribution

It introduces a self-consistent method to determine ferromagnetic phase boundaries in nuclear matter considering baryon dipole moments and magnetic interactions.

Findings

Ferromagnetism occurs when baryon dipole moments are increased by a factor of 35.

Crossing the phase boundary induces magnetic fields of about 10^{17} gauss.

The phase boundary is sensitive to nuclear matter parameterizations.

Abstract

Ferromagnetism in infinite neutron matter as well as beta equilibrated, charge neutral, dense, and infinite nuclear matter is investigated using a model of interacting baryons and mesons. The standard minimal couplings between the magnetic field and the particle charges as well as the baryon dipole moments are included in the Lagrangian density. Minimizing the energy density with respect to the magnetic field yields a self-consistent expression for the ferromagnetic field. We calculate the phase boundary at a given density by increasing the strength of the baryon dipole moments till the energy density of magnetized matter is lower than that of unmagnetized matter. We find that, depending on the density, it is crossed when the baryon dipole moments are increased by a factor of 35. It is also sensitive to the details of the nuclear matter parameterizations and crossing it induces a magnetic field of $\sim 10^{17}$ gauss.