  According to the partially screened gap scenario, an efficient
electron-positron pair creation, a general precondition of radio-pulsar
activity, relies on the existence of magnetic spots, i.e., local concentrations
of strong and small scale magnetic field structures at the surface of neutron
stars. They have a strong impact on the surface temperature, which is
potentially observable. Here we reinforce the idea that such magnetic spots can
be formed by extracting magnetic energy from the toroidal field that resides in
deep crustal layers, via Hall drift. We study and discuss the magneto-thermal
evolution of qualitatively different neutron star models and initial magnetic
field configurations that lead to the creation of magnetic spots. We find that
magnetic spots can be created on a timescale of $10^4$ years with magnetic
field strengths $\gtrsim 5\times 10^{13}$ G, provided almost the whole magnetic
energy is stored in its toroidal component, and that the conductivity in the
inner crust is not too large. The lifetime of the magnetic spots is at least
$\sim$one million of years, being longer if the initial field permeates both
core and crust.
