STSM of Timur Griener at London Center of Nanotechnology: Nanopatterning of superconducting Nb thin film devices with a focused Ne ion beam

The main purposes of this STSM were to exchange knowledge in focused ion-beam (FIB) modification of superconductors between the research groups at the University of Tübingen and the London Center of Nanotechnology (LCN) at the University College London and to explore a possible research collaboration between both groups. The groups cooperated in the new field of HNIM (Helium/Neon ion microscopes)-based fabrication and studies of new types of advanced superconducting nanoscale devices and circuits. The STSM enabled them to demonstrate the feasibility of realizing advanced superconducting quantum interference devices at the nanoscale (nanoSQUIDs) from Nb thin film constriction Josephson junctions (cJJs) by Ne-FIB patterning.

As a main result, the handling and special techniques and tricks used by the London group and their different members in HNIM-based nanoSQUID and cJJ fabrication have been explained. In several fruitful discussions, the different approaches at London and Tübingen in the nanostructuring procedure have been compared. Aspects discussed included how to form the trimer, mount the sample or focus, measurement techniques and many more.

Besides this detailed exchange of knowledge, the newly gained knowledge was applied to the fabrication of 53 cJJs and 17 nanoSQUIDs. This allowed a comparison of different fabrication techniques and contributed a lot to advancing nanopatterning by HNIM at the University of Tübingen.