R. Leoni et al., THIN-FILM TECHNOLOGY AND DC-SQUID INSTRUMENTATION FOR A SUPERHEATED SUPERCONDUCTING DETECTOR, Journal of low temperature physics, 93(3-4), 1993, pp. 503-508
We report on improvements of the dc-SQUID instrumentation developed to
study superheating-supercooling transitions of thin-film indium dots.
In previous measurements on ordered arrays of dots with diameters lar
ger than 100 mum the flip signal of an individual dot in perpendicular
magnetic field has been detected. In order to use these dots as super
heated superconducting detectors it is necessary to reduce the dot dia
meter to lower the energy threshold and to avoid intermediate states.
For these reasons, our effort has been to develop small and thick dots
with diameter down to 10 mum and thickness up to 3.5 mum. At the same
time the coupling with the dc-SQUID readout was improved using a thin
-film niobium pickup coil integrated on the same chip containing the d
ots. Phase transitions of individual dots were observed. The superheat
ing phase transition spread in temperature of the samples was about 0.
15 %.