Development of high sensitive magnetic contaminant detection system using an HTS-rf-SQUID covered with HTS thin films

Abstract

For high sensitive detection of magnetic contaminant in electrode of lithium-ion battery, high-temperature superconductor (HTS) radio-frequency (rf) superconducting quantum interference devices (SQUIDs) based on a bicrystal SrTiO3 (STO) substrate was designed, and fabricated employing YBa2Cu3O7−x thin films of about 200 nm in thickness. To improve characteristics such as effective area and 1/f noise profile of the SQUID, HTS thin films on normal STO substrates were overlapped on a wide superconducting weak link and/or a slit of the SQUID in flip-chip configuration. The noise profiles of the SQUID covered with the films on the respective positions were well improved compared to that of the bare SQUID. A magnetic contaminant detection system was developed employing the HTS-rf-SQUID covered with the films on both the positions. Using this system, a tungsten ball of 30 μm in diameter was successfully detected with a signal to noise ratio of about 14.