Spatial scanning of the synchronously generated 2nd and 3rd order
intermodulation distortion in superconducting resonators uncovers local
nonlinearity hot spots, and possible time reversal symmetry breaking, using a
simple probe fashioned from coaxial cable. It is clear that even and odd order
nonlinearity in these samples do not share the same physical origins, as their
temperature and static magnetic field dependences are quite different. 2nd
order intermodulation distortion (IMD) remains strong in these measurements as
the temperature continues to drop below TC to 77K even though the 3rd order
peaks near TC and becomes smaller at lower temperature as predicted by the
nonlinear Meissner effect. Both YBa2Cu3O7 and Tl2Ba2CaCu2O8 resonators of the
same structure exhibit similar temperature dependence in the 2nd order with 2nd
order remaining high at lower temperature. The YBa2Cu3O7 sample has lower 3rd
order IMD with a pronounced peak at TC
