Slide 20 of 59
Notes:
Substituting typical values into the relationship for t, we find a value for the decay time of a neutron star of 3000 years. However, since the magnetic field is still very intense after 1000 years, we must conclude that the interior of the neutron star is superconducting, ie the conductivity and thus the lifetime are both very large.
It is interesting at this point to consider the internal structure of neutron stars.
Neutron stars are extremely dense stars, where it is the zero-temperature energy (the Fermi energy) of the particles, rather than their thermal energy, which supports the star and prevents further collapse.
See Smith p36, Longair p84