  Thermal behavior of isoscalar and isovector proton-neutron (pn) pairing
energies at finite temperature are investigated by the shell model
calculations. These pn pairing energies can be estimated by double differences
of "thermal" energies which are extended from the double differences of binding
energies as the indicators of pn pairing energies at zero temperature. We found
that the delicate balance between isoscalar and isovector pn pairing energies
at zero temperature disappears at finite temperature. When temperature rises,
while the isovector pn pairing energy decreases, the isoscalar pn pairing
energy rather increases. We discuss also the symmetry energy at finite
temperature.
