Nanoscale superconductor-normal metal-superconductor junctions fabricated by focused ion beam

摘要

We have developed a reliable and versatile technique for fabricating low T_C superconductor-normal metal-superconductor Josephson junctions with a focused ion beam (FIB) microscope in conjunction with an in situ resistance measurement technique. This provides a simple method that allow us to create a variety of single and multi-junction superconducting devices (arrays, SQUIDs and 3 terminal devices) with desirable and well-controlled properties and high integration densities. Here we discuss the development of this technique, demonstrating the versatility of the FIB in this application with recent results from arrays intended for voltage standards, devices with novel circular junction geometry, and devices fabricated in MgB_2.