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

TL;DR

This study investigates local nonlinearities in superconducting microwave resonators made from Y-Ba-Cu-O and Tl-Ba-Ca-Cu-O, revealing distinct physical origins for even and odd order nonlinearities and their temperature dependencies.

Contribution

It demonstrates that even and odd order nonlinearities in these superconductors have different physical origins and dependences on temperature and magnetic field.

Findings

2nd order IMD remains strong below TC at 77K.

3rd order IMD peaks near TC and diminishes at lower temperatures.

YBa2Cu3O7 shows lower 3rd order IMD with a peak at TC.

Abstract

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.