Characteristics of the Superconducting-Quantum- Interference-Grating Magnetometer Consisting of Grain-Boundary Josephson Junctions

The characteristics of the magnetometer based on the superconducting quantum interference grating (SQIG) consisting of multiple high-T
_c
grain-boundary Josephson junctions were investigated. In comparison with the two-junction superconducting quantum interference device (SQUID), an enhancement in the flux-to-voltage transfer function by a factor of 4.6 was achieved. Moreover, a sharp increase in the flux-to-current transfer function by a factor of 45 was observed for the case with the screening parameter much less than unity. The estimated white magnetic flux noise of the SQIG is lower than that of the conventional SQUID by one order of magnitude.