Title :
Effects of flux dam on low-frequency noise in high-Tc SQUID magnetometers
Author :
Oyama, H. ; Kuriki, S. ; Matsuda, M.
Author_Institution :
Res. Inst. for Electr. Sci., Hokkaido Univ., Sapporo, Japan
fDate :
3/1/2001 12:00:00 AM
Abstract :
We demonstrated that the low-frequency noise in a high-Tc superconducting quantum interference device (SQUID) magnetometer when an external magnetic field is changed could be reduced by forming slots in a flux dam. We designed and fabricated directly coupled dc SQUID magnetometers having a mesh structure and flux dams. In order to suppress the vortex motion in the flux dams, we formed 5-μm-wide strip lines and slots across the grain boundary of the flux dams. The output of the magnetometer in a flux-locked loop (FLL) operation became stable and low-frequency noise was suppressed up to an applied field of 83 μT in field cooling and 40 μT for field change after zero field cooling. The importance of the structure of the flux dam in controlling the vortex motion is discussed
Keywords :
SQUID magnetometers; flux flow; high-temperature superconductors; superconducting device noise; 5 mum; SrTiO3; YBa2Cu3O7-SrTiO3; directly coupled dc SQUID magnetometers; field cooling; flux dam; flux-locked loop operation; grain boundary; high-Tc SQUID magnetometers; low-frequency noise; mesh structure; slots; stable output; strip lines; unshielded environment; vortex motion suppression; zero field cooling; Cooling; Couplings; Grain boundaries; Interference; Low-frequency noise; Magnetic fields; SQUID magnetometers; Strips; Superconducting device noise; Superconducting devices;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
