Magnetization of a neutron plasma with Skyrme and Gogny forces in the presence of a strong magnetic field

TL;DR

This study investigates the magnetization behavior of a pure neutron plasma under strong magnetic fields using Skyrme and Gogny forces within a non-relativistic Brueckner-Hartree-Fock framework, revealing differences in polarization trends and phase transition predictions.

Contribution

It compares Skyrme and Gogny effective nuclear interactions in predicting neutron plasma magnetization and phase transitions under strong magnetic fields.

Findings

Moderate temperatures and low densities allow strong magnetization as density decreases.

Gogny forces prevent ferromagnetic phase transition, maintaining magnetization below 5%.

Skyrme forces predict a ferromagnetic phase transition at higher densities.

Abstract

Some thermodynamical magnitudes of interest in a pure neutron plasma are studied within the framework of the non-relativistic Brueckner-Hartree-Fock approximation at finite density and temperature. We use Skyrme and Gogny forces to describe such a neutron plasma and study the main differences that arise in these two effective parametrizations of the nuclear interaction when a strong magnetic field induces a permanent magnetization in the gas. The existence of a non-zero permanent spin polarization in a neutron plasma is explored in the density-temperature parameter space. We find that for moderate temperatures and in the low density range up to densities $\approx 0.5\rho_0$ both parametrizations predict that as density decreases an increasingly strong magnetization is allowed. In the range $0.5 \rho_0 \lesssim \rho \lesssim 3 \rho_0$ there is an approximately constant polarization that can be as big as $\approx 12%$ for the maximum allowed interior magnetic field $B \approx 10^{18}$ G. For higher densities there is a dramatic difference in the polarization trend followed by Skyrme an Gogny forces. While the former predict a ferromagnetic phase transition, the Gogny forces prevent it keeping the magnetization below 5%.