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Title: Observation of 0–π transition in SIsFS Josephson junctions

Abstract

The 0–π 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′ | AlO{sub x} | Nb | Ni{sub 60}Cu{sub 40} | Nb JJs with wedge-like s (Nb) and F (Ni{sub 60}Cu{sub 40}) layers and studied the Josephson effect as a function of the s- and F-layer thickness, d{sub s} and d{sub F}, respectively. For d{sub s} = 11 nm, π-JJs with SIFS-type j{sub c}(d{sub F}) and critical current densities up to j{sub c}{sup π}=60 A/cm{sup 2} were obtained at 4.2 K. Thicker d{sub s} led to a drastic increase of the critical current decay length, accompanied by the unexpected disappearance of the 0–π transition dip in the j{sub c}(d{sub F}) dependence. Our results are relevant for superconducting memories, rapid single flux quantum logic circuits, and solid state qubits.

Authors:
; ;  [1]; ; ; ; ;  [2]
  1. Nanoelektronik, Technische Fakultät, Christian-Albrechts-Universität zu Kiel, Kaiserstr. 2, 24143 Kiel (Germany)
  2. Physikalisches Institut and Center for Collective Quantum Phenomena in LISA"+, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen (Germany)
Publication Date:
OSTI Identifier:
22399118
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRITICAL CURRENT; CURRENT DENSITY; ELECTRIC CONTACTS; FERROMAGNETIC MATERIALS; FERROMAGNETISM; JOSEPHSON EFFECT; JOSEPHSON JUNCTIONS; LAYERS; LOGIC CIRCUITS; QUBITS; SEMICONDUCTOR JUNCTIONS; SOLIDS; SUPERCONDUCTORS; TUNNEL EFFECT

Citation Formats

Ruppelt, N., E-mail: nru@tf.uni-kiel.de, Vavra, O., Kohlstedt, H., Sickinger, H., Menditto, R., Goldobin, E., Koelle, D., and Kleiner, R.. Observation of 0–π transition in SIsFS Josephson junctions. United States: N. p., 2015. Web. doi:10.1063/1.4905672.
Ruppelt, N., E-mail: nru@tf.uni-kiel.de, Vavra, O., Kohlstedt, H., Sickinger, H., Menditto, R., Goldobin, E., Koelle, D., & Kleiner, R.. Observation of 0–π transition in SIsFS Josephson junctions. United States. doi:10.1063/1.4905672.
Ruppelt, N., E-mail: nru@tf.uni-kiel.de, Vavra, O., Kohlstedt, H., Sickinger, H., Menditto, R., Goldobin, E., Koelle, D., and Kleiner, R.. Mon . "Observation of 0–π transition in SIsFS Josephson junctions". United States. doi:10.1063/1.4905672.
@article{osti_22399118,
title = {Observation of 0–π transition in SIsFS Josephson junctions},
author = {Ruppelt, N., E-mail: nru@tf.uni-kiel.de and Vavra, O. and Kohlstedt, H. and Sickinger, H. and Menditto, R. and Goldobin, E. and Koelle, D. and Kleiner, R.},
abstractNote = {The 0–π 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′ | AlO{sub x} | Nb | Ni{sub 60}Cu{sub 40} | Nb JJs with wedge-like s (Nb) and F (Ni{sub 60}Cu{sub 40}) layers and studied the Josephson effect as a function of the s- and F-layer thickness, d{sub s} and d{sub F}, respectively. For d{sub s} = 11 nm, π-JJs with SIFS-type j{sub c}(d{sub F}) and critical current densities up to j{sub c}{sup π}=60 A/cm{sup 2} were obtained at 4.2 K. Thicker d{sub s} led to a drastic increase of the critical current decay length, accompanied by the unexpected disappearance of the 0–π transition dip in the j{sub c}(d{sub F}) dependence. Our results are relevant for superconducting memories, rapid single flux quantum logic circuits, and solid state qubits.},
doi = {10.1063/1.4905672},
journal = {Applied Physics Letters},
number = 2,
volume = 106,
place = {United States},
year = {Mon Jan 12 00:00:00 EST 2015},
month = {Mon Jan 12 00:00:00 EST 2015}
}