Increasing the sensor performance using Au modified high temperature superconducting YBa₂Cu₃O_7-δ thin films

We prepared planar, galvanically coupled gradiometers whereby the antenna structures of some of them were modified by incorporating Au nanoparticles. Gradiometers with gold modified antennas were compared with conventional ones to investigate the influence of gold induced pinning on the performance of superconducting sensor devices. We found that a local inclusion of gold nanoparticles offers the possibility of increasing the pinning of flux lines in the antenna regions, thus significantly reducing flux noise, especially in the low-frequency range. Since also the properties of grain boundary Josephson Junctions are strongly affected by Au particles, SQUID and antenna regions in gradiometric sensor devices can be separately optimized.