Fabrication of weak-link Nb-based nano-SQUIDs by FIB process

作者：Matsumoto T; Kashiwaya H^*; Shibata H; Takayanagi H; Nomura S; Kashiwaya S

来源：Physica C-Superconductivity and Its Applications, 2011, 471(21-22): 1246-1248.

DOI：10.1016/j.physc.2011.05.170

• Nano-SQUID
• Weak-link
• Nb

We develop a fabrication process of Nb-based nano-SQUIDs (superconducting quantum interference devices) containing two weak-link Josephson junctions patterned by a focused ion beam (FIB). Typical dimension of the SQUID diameter was 1 mu m, and the widths of the weak links were changed in the range of 60 and 500 nm. In order to evaluate the degradation of Nb due to the FIB process, we employed bilayer films of Nb/Au and Nb/W in addition to single layer Nb films. The lateral degradation depths of 85 nm for Nb and 27.5 nm for Nb/Au and Nb/W indicate that the normal metals successfully work as the protection layer. The magnetic field dependence of the critical current showed the modulation ratio of about 10%.

• 出版日期2011-11