Selected error sources in resistance measurements on superconductors

In order to investigate the causes that produce some of the unwanted effect s observed in the resistance versus temperature profiles, a variety of sour ces of error for resistance measurements in superconductors, using a standa rd four-probe configuration, have been studied. A piece of superconducting Y1Ba2Cu3O7-x ceramic material has been used as the test sample, and the res ulting effects in both accuracy and precision in its temperature dependent resistance are reported here. Studied measurement error sources include the rmal emf's, temperature sweep rates, Faraday currents, electrical-contact f ailures at the sample's surface, thermal contractions at mechanically attac hed instrumental wires, external electromagnetic fields, and slow sampling rates during data acquisition. Details of the experimental setup and its me asurement error function are also given. (C) 2001 American Institute of Phy sics.