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Ferromagnetism in neutron and charge neutral beta-equilibrated nuclear matter

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.