Development of Integrated HTS SQUIDs With a Multilayer Structure and Ramp-Edge Josephson Junctions

作者：Wakana Hironori^*; Adachi S; Hata Kiyoshi; Hato Tsunehiro; Tarutani Yoshinobu; Tanabe Keiichi

来源：IEEE Transactions on Applied Superconductivity, 2009, 19(3): 782-785.

DOI：10.1109/TASC.2009.2019077

• High-temperature superconductors
• SQUIDs
• superconducting device fabrication
• superconducting device noise

We have fabricated high-temperature superconductor (HTS) dc superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge Josephson junctions. For stable operation at 77 K, SmBa(2)Cu(3)Oy (SmBCO) and La(0.1) - Er(0.95)Ba(1.95)Cu(3)Oy (La-ErBCO) films with a T(c) above 90 K were employed as materials for the base-electrode and counter-electrode layers, respectively. Junctions were fabricated by employing a Cu-poor La-ErBCO layer as a precursor of the barrier. The fabricated parallel gradiometers with a baseline of 1-3 mm exhibited the field-induced modulation voltage of 20-50 mu V at 77 K, and a clear modulation up to 86.8 K. Noise measurements at 77 K revealed a white flux noise of 4.5-10 mu Phi(0)/Hz(1/2) at 1 kHz. The magnetometer with an integrated 20-turn flux transformer and the effective area of about 1.8 mm(2) exhibited a field noise of 25 fT/Hz(1/2) or less at 1 kHz.

• 出版日期2009-6