  It is well known that neutron stars spin down due to magnetic dipole
radiation. The deconfinement phase transition of hadron matter to quark matter
is expected to occur in the dense cores of the stars during spin-down. The
phase transition continuously takes place inducing not only structural changes
but also energy release in case of a first-order phase transition. The
generation of energy increases the internal energy of the stars which is called
deconfinement heating. The temperature of the stars arise when the
deconfinement heating appears in the cores. We explore the deconfinement
signature by studying the changes of surface temperature in the thermal
evolution process of neutron stars.
