https://doi.org/10.1140/epjb/e2007-00210-8
0-π oscillations in nanostructured Nb/Fe/Nb Josephson junctions
1
Department of Materials Science, University of Cambridge - Pembroke Street, Cambridge, CB2 3QZ, UK
2
Physics Department, CNR-Supermat Laboratory, University of Salerno - Via S. Allende, 84081 Baronissi (SA), Italy
3
School of Physics and Astronomy, E.C. Stoner Laboratory, University of Leeds, Leeds-LS2 9, JT, UK
Corresponding author: a samanta.piano@gmail.com
Received:
13
March
2007
Revised:
11
May
2007
Published online:
1
August
2007
The physics of the π phase shift in ferromagnetic Josephson junctions may enable a range of applications for spin-electronic devices and quantum computing. We investigate transitions from “0” to “π” states in Nb/Fe/Nb Josephson junctions by varying the Fe barrier thickness from 0.5 nm to 5.5 nm. From magnetic measurements we estimate for Fe a magnetic dead layer of about 1.1 nm. By fitting the characteristic voltage oscillations with existing theoretical models we extrapolate an exchange energy of 256 meV, a Fermi velocity of 1.98 ×105 m/s and an electron mean free path of 6.2 nm, in agreement with other reported values. From the temperature dependence of the ICRN product we show that its decay rate exhibits a nonmonotonic oscillatory behavior with the Fe barrier thickness.
PACS: 74.50.+r – Tunneling phenomena; point contacts, weak links, Josephson effects / 74.25.Sv – Critical currents / 74.78.Db – Low-Tc films / 74.25.Ha – Magnetic properties
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007
