Observation of 0-π transition in SIsFS Josephson junctions

被引：17
作者：
Ruppelt, N. [1 ]
Sickinger, H. [2 ,3 ]
Menditto, R. [2 ,3 ]
Goldobin, E. [2 ,3 ]
Koelle, D. [2 ,3 ]
Kleiner, R. [2 ,3 ]
Vavra, O. [1 ]
Kohlstedt, H. [1 ]
机构：
[1] Univ Kiel, Tech Fak, D-24143 Kiel, Germany
[2] Univ Tubingen, Inst Phys, D-72076 Tubingen, Germany
[3] Univ Tubingen, Ctr Collect Quantum Phenomena LISA, D-72076 Tubingen, Germany
来源：
APPLIED PHYSICS LETTERS | 2015年 / 106卷 / 02期
关键词：
TUNNEL-JUNCTIONS; FERROMAGNET; ELECTRONICS; FABRICATION; CIRCUITS;
D O I：
10.1063/1.4905672
中图分类号：
O59 [应用物理学];
学科分类号：
摘要：
The 0-pi transition in Superconductor-Insulator-superconductor-Ferromagnet-Superconductor (SIsFS) Josephson junctions (JJs) was investigated experimentally. As predicted by theory, an s-layer inserted into a ferromagnetic SIFS junction can enhance the critical current density up to the value of an SIS tunnel junction. We fabricated Nb'vertical bar AlOx vertical bar Nb vertical bar Ni60Cu40 vertical bar Nb JJs with wedgelike s (Nb) and F (Ni60Cu40) layers and studied the Josephson effect as a function of the s- and F-layer thickness, d(s) and d(F), respectively. For d(s) = 11 nm, pi-JJs with SIFS-type j(c)(d(F)) and critical current densities up to j(c)(pi) = 60A/cm(2) were obtained at 4.2 K. Thicker d(s) led to a drastic increase of the critical current decay length, accompanied by the unexpected disappearance of the 0-pi transition dip in the j(c)(d(F)) dependence. Our results are relevant for superconducting memories, rapid single flux quantum logic circuits, and solid state qubits. (C) 2015 AIP Publishing LLC.
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页数：4
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