Title :
Integrated multilayer high-Tc SQUID magnetometers with slotted washer
Author :
Lee, H.J. ; Park, W.K. ; Lee, S.-M. ; Park, J.D. ; Moon, S.H. ; Oh, B.
Author_Institution :
LG Electron. Inst. of Technol., Seoul, South Korea
fDate :
3/1/2001 12:00:00 AM
Abstract :
We have fabricated and characterized multilayer high-Tc SQUID magnetometers designed for a magnetically unshielded environment. The magnetometers consist of YBa2Cu3O7-x(YBCO)/SrTiO3 (STO)/YBCO trilayers deposited by pulsed laser deposition (PLD) on an STO bi-crystal substrate. We fabricated SQUIDs with slotted washers at the bottom or top YBCO layer. The slots consist of 4 μm wide superconducting lines separated by 8 μm. A flux transformer with a multi-turn input coil was defined on the top or bottom YBCO layer, and the SQUID washer was used as a crossover pattern to simplify the fabrication process. The pickup loop size was 4 mm×7 mm, and the magnetometer effective area was found to be 0.67 mm2. The SQUID inductance was 85 pH. For the operation of our SQUID in unshielded environments, compact 3 MHz modulation flux locked loop (FLL) electronics with bias-reversal were developed. The system bandwidth was greater than 500 kHz, and maximum slew rate was about 106 Φ0/sec. The flux noise spectra of the magnetometers were measured and compared with our single layer devices. We also investigated the effect of slots on the coupling strength between the input coil and SQUID
Keywords :
SQUID magnetometers; barium compounds; high-temperature superconductors; pulsed laser deposition; readout electronics; superconducting device noise; superconducting integrated circuits; superconductor-insulator-superconductor devices; yttrium compounds; 3 MHz modulation flux locked loop electronics; 4 mum; 500 kHz; SQUID inductance; SQUID washer; SrTiO3; SrTiO3 bicrystal substrate; YBa2Cu3O7-x/SrTiO3 /YBa2Cu3O7-x trilayers; YBa2Cu3O7-SrTiO3-YBa 2Cu3O7; bias-reversal; crossover pattern; flux noise spectra; flux transformer; input coil coupling strength; integrated multilayer high-Tc SQUID magnetometers; magnetically unshielded environment; magnetometer effective area; maximum slew rate; multi-turn input coil; pickup loop size; pulsed laser deposition; slotted washer; superconducting lines; system bandwidth; Magnetic flux; Magnetic multilayers; Magnetic separation; Nonhomogeneous media; Optical pulses; Pulsed laser deposition; SQUID magnetometers; Superconducting coils; Superconducting magnets; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
