Magnetic imaging of YBa 2Cu 3O y sampler circuits with moats by a scanning SQUID microscope
Abstract
We have investigated the flux state in YBa2Cu3Oy (YBCO) sampler circuits having superconducting ground planes with 5 or 7-μm-wide moats by a scanning SQUID microscope (SSM) system. It was found that magnetic flux was trapped into continuous moats with the length larger than 20 μm, and magnetic flux was excluded from the moat-surrounded area which includes ramp-edge Josephson junctions and ground plane contacts. We ensured that flux trapping into ground plane contacts is suppressed by reducing its size to typically 5 × 5 μm2. The threshold value for complete flux exclusion is about 0.8 μT slightly depending on chips, which can be readily achieved with dual μ-metal magnetic shielding. In addition, we have observed the magnetic flux due to electric noise which comes from outside the SSM chamber.
- Publication:
-
Physica C Superconductivity
- Pub Date:
- October 2005
- DOI:
- 10.1016/j.physc.2005.02.129
- Bibcode:
- 2005PhyC..426.1668S
- Keywords:
-
- YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> sampler circuit;
- Scanning SQUID microscope;
- Multilayer structure;
- Moat;
- Superconducting ground plane;
- Ground plane contact;
- 74.60.Ge;
- 74.72.Bk;
- 85.25.-j;
- 85.25.Cp;
- 85.25.Am;
- Y-based cuprates;
- Superconducting devices;
- Josephson devices;
- Superconducting device characterization design and modeling
