Abstract
We report the results of a study of the current gain in high Josephson critical current density (jc ) superconductingferromagnetic transistors with the SISFIFS structure [where S, I, and F denote a superconductor (Nb), an insulator (AlOx), and a ferromagnetic material (permalloy, Py), respectively]. The Nb/AlOx/Nb trilayer, which serves as the acceptor (SIS) junction, is estimated to have Josephson critical current density jc of 19 kA/cm2. The Al/Py/Al/AlOx/Py/Al/Nb multilayer is deposited in a separate vacuum run after in situ ionmilling of about 8 nmof the top Nb layer. The devices are patterned using optical lithography and tested at 4.2 K. We have observed a small-signal current gain in the range of 5-9.We demonstrate that proper device engineering allows one to efficiently control the maximum Josephson current in the SISF acceptor junction using the quasiparticle injection.
Original language | English (US) |
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Article number | 7779084 |
Journal | IEEE Transactions on Applied Superconductivity |
Volume | 27 |
Issue number | 4 |
DOIs | |
State | Published - Jun 2017 |
Keywords
- Josephson effect
- Superconducting-ferromagnetic hybrid structures
- proximity effect
- quasiparticle injection
- superconducting transistor
- superconductivity
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering