High-frequency analysis of superconducting device by using microwave equivalent circuit

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420347
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electron device/Electronic equipment
• Research Institution: Kanagawa University
• Principal Investigator: Nakayama Akiyoshi 神奈川大学, 工学部, 教授 (90183524)
• Co-Investigator(Kenkyū-buntansha): ABE Susumu 神奈川大学, 工学部, 准教授 (10333147) ; ANADA Tetsuo 神奈川大学, 工学部, 教授 (20260987)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 超伝導 / トンネル素子 / ジョセフソン接合 / マイクロ波回路 / 磁界変調特性

Outline of Final Research Achievements

By using niobium (Nb) superconducting material and aluminum (Al) metal, we have fabricated Nb/Al-oxide/Nb Josephson tunnel junctions. Though Nb/Al-oxide/Nb superconducting junctions a current can flow without voltage drop at liquid helium temperature (4.2K), where the critical current value can be modulated by an external magnetic field. In the current-voltage characteristics of this superconducting junction, both the superconducting current and the resonant current steps at a finite voltage can be observed. The microwave would propagate perpendicular direction to an external magnetic field inside the junction tunnel-oxide region. The microwave frequency is proportional to the voltage value (50GHz---0.1mV). We can explain these phenomena using our new plain microwave circuit model.

Free Research Field

超伝導デバイス