Surface energy of magnetized superconducting matter in the neutron star cores

Abstract

In this paper, an effective field theory for proton superconductor (SC) interacting with neutron superfluid (SF), both with scalar order parameters, is developed and applied to the surface energy (SE) of a magnetized SC body in neutron stars (NS). Essentially, the SE studied here differs from the nuclear SE: here, the proton SF density decays to zero while the total proton density is constant across the surface. Interactions between the condensates are parameterized phenomenologically and their effects determined from calculations of a planar SE as the ranges of parameters are varied. The critical Ginzburg-Landau (GL) parameter ${\kappa }_c$ which renders the SE equal to zero is found analytically by noting that in a system with vanishing SE the thermodynamic critical MF is equivalent to the upper critical MF. In the case of weak coupling, ${\kappa }_c$ is shown to be a linear function of SF-SF density-density coupling, in agreement with the earlier results based on asymptotic intervortex interactions. Numerical simulations corroborate our analytical predictions. Coupling due to the mixed term arising from a scalar product of gradients of the SF densities, which had been considered in the earlier literature, is seen to have practically no effect on the superconductivity type. However, this coupling does produce a frozen wave packet of the SF neutron density localized at the surface. It is shown that the leading contribution from the gradient coupling arises from a novel mixed quantum pressure term, but still does not affect the planar SE. The present calculations provide an initial map of superconductivity types in the phenomenological effective field theory and will serve as a landmark for future studies, which require microscopic calculations of the coupling parameters introduced here phenomenologically.

arXiv comment15 pages, 3 figures. Published 9 October 2020

References in corpus (22)

• Neutron star magnetic field evolution, crust movement and glitches
• Constraining Hadronic Superfluidity with Neutron Star Precession
• Magnetohydrodynamics of superfluid and superconducting neutron star cores
• Polarization contributions to the spin-dependence of the effective interaction in neutron matter
• R-Modes in Superfluid Neutron Stars
• Variational description of multi-fluid hydrodynamics: Uncharged fluids
• Magnetic fields in superconducting neutron stars
• Neutron Stars as Type-I Superconductors
• A Relativistic Mean Field Model for Entrainment in General Relativistic Superfluid Neutron Stars
• Magnetar superconductivity versus magnetism: neutrino cooling processes
• Pairing in neutron matter: New uncertainty estimates and three-body forces
• Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid
• Stability of interlinked neutron vortex and proton flux tube arrays in a neutron star: equilibrium configurations
• Critical magnetic fields in a superconductor coupled to a superfluid
• Andreev-Bashkin effect and knot solitons in interacting mixture of a charged and a neutral superfuids with possible releveance for neutron stars
• Thermodynamics of uncharged relativistic multifluids
• Unconventional rotational responses of hadronic superfluids in a neutron star caused by strong entrainment and a ${\Sigma }^{-}$ hyperon gap
• Vortices and type-I superconductivity in neutron stars
• Isospin asymmetry and type-I superconductivity in neutron star matter
• Dispersion and decay of collective modes in neutron star cores
• Two-component superfluid hydrodynamics of neutron star cores
• Application of superconducting-superfluid magnetohydrodynamics to nuclear "pasta" in neutron stars