Flexible, automatic test system for characterizing superconducting junctions and devices

Abstract

A system has been designed for the characterizing of both low and high T, junctions and devices. Fully automateId measurements of resistance versus temperature, current versus voltage, and critical current versus applied field can be carried out on up to eight devices in one cooldown cycle. The system has been proven to reduce the repetitive nature and time involved in characterizing many junctions and devices, and greatly speeds up the analysis of changes in their parameters. Connections are made to the sample using spring contacts which eliminate the need for soldering to contact pads. One or two substrates with ten connections per substrate can be placed in the probe at the one time. A microcomputer with an IEEE488 interface, four standard instruments (two constant current sources, one digital multimeter, and one voltmeter), and a specially designed probe and software has been incorporated to provide a system which is very flexible and yet very simple to operate.

New techniques for fabricating step-edge junctions for high-T/sub c/ SQUIDs on MgO substrates

“…This left some residual insulating film of 10-30nm in some cases. Samples were measured in a four-terminal configuration to obtain R-T, I-V and I,-B characteristics using an automated measurement system [9].…”

Flux noise in ion-implanted nanoSQUIDs

“…Transport measurements of bonded devices were performed over a range of temperatures down to 4.2 K using Star Cryoelectronics DC SQUID drive electronics with nV Hz −1/2 sensitivity [16]. Current-voltage (I -V ) curves were obtained for all devices as a function of temperature.…”

NanoSQUID detection of magnetization from ferritin nanoparticles

“…Having attached the ferritin nanoparticles to the nanoSQUID, measurements were carried out to observe flux changes resulting from the ferritin magnetic moments. The magnetization measurements were done at a temperature of 4.2 K by mounting the nanoSQUID and field-coil assembly on a cylindrical probe which was encased in a mu-metal shield and inserted into a liquid helium cryostat [50]. During the cooling phase, the applied field was off and only the ambient field in the lab, attenuated by the shield, was present.…”