The equation of state of neutron matter is affected by the presence of a magnetic field due to the intrinsic magnetic moment of the neutron .
Here we study the equilibrium configuration of this system for a wide range of densities , temperatures and magnetic fields .
Special attention is paid to the behavior of the isothermal compressibility and the magnetic susceptibility .
Our calculation is performed using both microscopic and phenomenological approaches of the neutron matter equation of state , namely the Brueckner–Hartree–Fock ( BHF ) approach using the Argonne V18 nucleon-nucleon potential supplemented with the Urbana IX three-nucleon force , the effective Skyrme model in a Hartree–Fock description , and the Quantum Hadrodynamic formulation with a mean field approximation .
All these approaches predict a change from completely spin polarized to partially polarized matter that leads to a continuous equation of state .
The compressibility and the magnetic susceptibility show characteristic behaviors , which reflect that fact .
Thermal effects tend to smear out the sharpness found for these quantities at T=0 .
In most cases a thermal increase of \Delta T = 10 MeV is enough to hide the signals of the change of polarization .
The set of densities and magnetic field intensities for which the system changes it spin polarization is different for each model .
However , we found that under the conditions examined in this work there is an overall agreement between the three theoretical descriptions .