Finite temperature effects on spin polarization of neutron matter in a strong magnetic field

Abstract

Spin polarization of neutron matter at finite temperatures and strong magnetic fields up to $10^{18}$ G is studied in the model with the Skyrme effective interaction. It is shown that, together with the thermodynamically stable branch of solutions for the spin polarization parameter corresponding to the case when the majority of neutron spins are oriented opposite to the direction of the magnetic field (negative spin polarization), the self-consistent equations, beginning from some threshold density, have also two other branches of solutions corresponding to positive spin polarization. The influence of finite temperatures on spin polarization remains moderate in the Skyrme model up to temperatures relevant for protoneutron stars, and, in particular, the scenario with the metastable state characterized by positive spin polarization, considered at zero temperature in Phys. Rev. C {\bf 80}, 065801 (2009), is preserved at finite temperatures as well. It is shown that above certain density the entropy for various branches of spin polarization in neutron matter with the Skyrme interaction in a strong magnetic field demonstrates the unusual behavior being larger than that of the nonpolarized state. By providing the corresponding low-temperature analysis, it is clarified that this unexpected behavior should be addressed to the dependence of the entropy of a spin polarized state on the effective masses of neutrons with spin up and spin down, and to a certain constraint on them which is violated in the respective density range.

Prepared with RevTeX4, 6pp., 4 figs; v2: accepted in JKAS

References in corpus (4)

• Spin polarized neutron matter within the Dirac-Brueckner-Hartree-Fock approach
• Magnetization of a neutron plasma with Skyrme and Gogny forces in the presence of a strong magnetic field
• Spin ordered phase transitions in isospin asymmetric nuclear matter
• Unusual temperature behavior of entropy of antiferromagnetic spin state in nuclear matter with effective finite range interaction

Cited by in corpus (3)

• Spin and spin-isospin instabilities in asymmetric nuclear matter at zero and finite temperatures using Skyrme functionals
• Stability of magnetized strange quark matter in the MIT bag model with the density dependent bag pressure
• Spin ordered phase transitions in neutron matter under the presence of a strong magnetic field