Low frequency voltage noise in high temperature superconductor Josephson junctions

Abstract

The origin of 1/f voltage noise in different types of Josephson junctions fabricated from the high temperature superconductors (HTS) have been traced back to the trapping and release of charge carriers in trapping centers in an insulating barrier giving rise to correlated fluctuations of the junction critical current I_c and normal state resistance R_n. For the normalized fluctuations S_I and S_R a linear scaling with R_n has been observed which suggests an almost constant density of trapping centers for all investigated HTS Josephson junctions. Using this linear scaling we have made an approximate calculation of the density of the trapping centers.