| Summary: | We suggest a mechanism that may resolve a conflict between the precession
of a neutron star and the widely accepted idea that protons in the bulk
of the neutron star form a type-II superconductor. We will show that if
there is a persistent, non-dissipating current running along the magnetic
flux tubes the force between magnetic flux tubes may be attractive, resulting
in a type-I, rather than a type-II, superconductor. If this is the case, the
conflict between the observed precession and the canonical estimation of the
Landau-Ginzburg parameter κ > 1 /[square root of 2] (which suggests type-II behaviour)
will automatically be resolved. We calculate the interaction between two
vortices, each carrying a current j , and demonstrate that when j > [formula omitted],
where q is the charge of the Cooper pair and λ is the Meissner penetration
depth, a superconductor is always type-I, even when the cannonical [sic] Landau-
Ginzburg parameter κ indicates type-II behaviour. If this condition is met,
the magnetic field is completely expelled from the superconducting regions
of the neutron star. This leads to the formation of the an intermediate
state, where alternating domains of superconducting matter and normal
matter coexist. We also discuss how these currents might lead to more
exotic vortex structures in neutron stars. === Science, Faculty of === Physics and Astronomy, Department of === Graduate
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