Paramagnetism of hot magnetic neutron gas

Abstract

Spontaneous magnetization and susceptibility of a noninteracting system of chargeless relativistic spin-½ magnetic moments in the presence of an intense magnetic field are calculated. We find that spontaneous magnetization is unlikely to occur and that the susceptibility parameter (X) obeys Curie-type behavior at high temperature (T), namely X=(1/2)(N/kT)μ_N², where N is the number density, k is the Boltzmann constant, and μ_N is the anomalous magnetic moment of the spin-½ object. These results are of direct interest to a neutron star where neutrons are considered to be the predominant constituent of matter and on its surface a magnetic field of strength ~ 10¹³ G is present. We also obtain the temperature-dependent corrections to the energy and number density of an ultradegenerate cold neutron star, which are necessary in connection with the equation of state of a hot neutron star.