Microwave Current Imaging in Passive HTS Components by Low-Temperature Laser Scanning Microscopy (LTLSM)

TL;DR

This paper demonstrates the use of Low-Temperature Laser Scanning Microscopy (LTLSM) to spatially resolve microwave transport properties and material inhomogeneities in a superconducting YBCO resonator, revealing effects of microstructural features on device performance.

Contribution

It introduces LTLSM as a tool for non-destructive, high-resolution analysis of microwave properties in superconducting HTS components, highlighting its potential for future applications.

Findings

Microstructural features affect current distribution

Edge currents influence device linearity

LTLSM enables detailed microwave property mapping

Abstract

We have used the LTLSM technique for a spatially resolved investigation of the microwave transport properties, nonlinearities and material inhomogeneities in an operating coplanar waveguide YBa_2Cu_3O_{7-\delta} (YBCO) microwave resonator on an LaAlO_3 (LAO) substrate. The influence of twin-domain blocks, in-plane rotated grains, and micro-cracks in the YBCO film on the nonuniform rf current distribution were measured with a micrometer-scale spatial resolution. The impact of the peaked edge currents and rf field penetration into weak links on the linear device performance were studied as well. The LTLSM capabilities and its future potential for non-destructive characterization of the microwave properties of superconducting circuits are discussed.