Relaxation of Microwave Nonlinearity in a Cuprate Superconducting Resonator

TL;DR

This study investigates the nonlinear microwave response of a YBa2Cu3O7 superconducting resonator, revealing distinct relaxation behaviors of second and third order intermodulation distortion after magnetic field removal.

Contribution

It introduces a local measurement technique for IMD in superconducting resonators and uncovers different relaxation mechanisms for 2nd and 3rd order nonlinearities.

Findings

2nd order IMD relaxes via fast and slow magnetic processes.

3rd order IMD relaxes through a distinct process from 2nd order.

Different relaxation behaviors are linked to magnetic phenomena in the superconductor.

Abstract

The 2nd and 3rd order nonlinear microwave response of a superconducting YBa2Cu3O7 thin film resonator was synchronously measured using three input tones. This technique permits the local measurement, and hence mapping, of intermodulation distortion (IMD) inside the resonator. 2nd and 3rd order IMD measured with a fixed probe relaxed in remarkably different ways after the removal of a static magnetic field. The 2nd order IMD relaxed by two different magnetic processes, a fast process that appears related to bulk remanent magnetization, and a slow process that fits the description of Bean and Livingston. The 3rd order IMD relaxes by only one process which is distinct from the two processes controlling 2nd order relaxation.