Estimation of Critical Current of HTS RF-SQUID. Issue 1 (July 2021)

• Record Type: Journal Article
• Authors: Ohtani, R; Hayashi, K; Sagawa, M; Ariyoshi, S; Tanaka, S
• Is Part Of: Journal of physics. Volume 1975:Issue 1(2021)
• Publication Date: 2021-07
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/1975/1/012022
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: The operation of the RF SQUID is restricted by the condition that the inductance parameter β L must be in the range of 1−3. However, since both ends of the Josephson junction (JJ) of RF-SQUID are shorted, it is difficult to non-destructively estimate the critical current ( IC ). Thus, we proposed a technique for the non-destructive measurement of the IC of a high-temperature superconducting (HTS) RF-SQUID ring by evaluating the behaviour of the flux in superconducting thin films using a SQUID magnetometer. A superconducting ring sample with JJ was placed below the HTS SQUID magnetometer and cooled down to 77 K. The change in the SQUID output was monitored on application of the magnetic field. When increasing the field, the waveforms indicated that the screening current of the ring sample exceeded the I C of the JJ, and the JJ became a normal-conducting state. As a result, we estimated the IC of the JJ of this sample as 134 μA using the values of mutual inductance and the coupling coefficient α between the coil and the sample.