SHUNTED YBCO BI-CRYSTAL JUNCTIONS FOR NOISE THERMOMETRY

We present experimental results on YBCO thin film bi-crystal junctions in which additional metallic shunt resistors are added by in-situ eva poration of gold or silver. These junctions are intended for use in th e development of an HTS Josephson noise thermometer for primary temper ature scale use. The temperature dependence of the critical current an d effective shunt resistance are reported and the noise arising from t he shunted junctions when biased into the finite voltage regime has be en assessed as a function of frequency. This is compared with the pred ictions of a simple model and the implications for the potential accur acy of the proposed thermometer are considered. Crown Copyright (C) 19 98 Published by Elsevier Science Ltd. All rights reserved.