Probing the Locally Generated Even and Odd Order Nonlinearity in Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O (2212) Microwave Resonators Around T_C

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Published on-line December 2012

Will appear in the June 2013 issue of IEEE Transactions on Applied Superconductivity


Spatial scanning of the synchronously generated 2^{nd} and 3^{rd} 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. 2^{nd} order intermodulation distortion (IMD) remains strong in these measurements as the temperature continues to drop below T_{C} to 77K even though the 3^{rd} order peaks near T_{C} and becomes smaller at lower temperature as predicted by the nonlinear Meissner effect. Both YBa_{2}Cu_{3}O_{7} and Tl_{2}Ba_{2}CaCu_{2}O_{8} resonators of the same structure exhibit similar temperature dependence in the 2^{nd} order with 2^{nd} order remaining high at lower temperature. The YBa_{2}Cu_{3}O_{7} sample has lower 3^{rd} order IMD with a pronounced peak at T_{C}.