Thermal effects on the resistive superconducting transition in step-edge YBCO squid arrays

Abstract The effect of thermal fluctuations in yttrium barium copper oxide SQUID filters (SQIFs), containing arrays of 258, 2304, and 4080 superconducting quantum interference devices (SQUIDs), were investigated using the electrical resistivity and applied magnetic field up to 9 T. Our study reveals that the SQIFs experience a two-step superconductor transition. The transition at lower temperature is only present in the SQIF samples, not in the control sample without the SQIFs, and it is investigated here in terms of two primary dissipation mechanisms. The first dominates near the transition temperature and has the characteristics of thermally activated phase slippage. At lower temperatures, the dominant characteristics are those of thermally-activated magnetic flux flow. The mechanisms producing such behaviors contribute significantly to dissipation effects, resulting in an additional DC voltage that overlays the Josephson current, regardless of the quantity of SQUIDs in the SQIFs. These dissipation effects can have significant implications for technologies utilizing high-temperature superconductor SQIFs unless the operating temperature is lowered significantly below the superconducting transition temperature.