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Ultrafast machining of high temperature superconductor nanostructures for novel mesoscale physics

High temperature superconductors (HTS) are novel materials that exhibit zero electrical resistance and exclusion of magnetic fields at temperatures over 77 K. The main aim of this project is to enhance the critical current density (Jc) of thin-film HTS bridges by creating edge-barrier pinning. Assuming a perfect edge, edge-barrier pinning effects bridges as large as 200 μm. This limit becomes smaller as edge quality degrades. Unlike photolithography, laser machining is a chemical free, flexible process; the use of an ultrafast laser gives minimal edge damage.

Student

Katjana Lange

Supervisor

Dr Martin Sparkes

Advisor

Professor Bill O'Neill

Project overview

One emerging area of research is the use of HTS mesoscopic structures to detect, generate, guide, and manipulate electromagnetic radiation across the microwave to infrared electromagnetic spectrum. Decreasing and sharpening feature size is expected to improve radiation efficiency, broaden bandwidth, and potentially leads to new fundamental physics.

Micromachining HTS, however, is a challenge. The material is very sensitive to heating and moisture. Because special care must be taken, this work focuses on ultrafast laser machining methodologies for manufacturing HTS mesoscopic structures using the ultrafast lasers available in the CIP labs.

The aim is to determine the smallest possible feature size on HTS thin films without degrading the superconductivity transport properties. These properties will be measured using Raman spectroscopy, SEM, and cryogenic transport measurements that will show changes in maximum sustainable current.

 

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