Regensburg 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 8: Postersitzung I: Supraleitung
TT 8.53: Poster
Montag, 8. März 2004, 14:30–19:00, Poster A
Josephson coupling in Nb/Al2O3/Cu1Ni1−x/Nb tunnel junctions — •Martin Weides1, Edward Goldobin2, Reinhold Kleiner2, and Hermann Kohlstedt1 — 1Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich — 2Physikalisches Institut-Experimentalphysik II, Universität Tübingen, D-72076 Tübingen
The realization of qubits for quantum computation attracts considerable interest. One of the approaches is to use π Josephson junctions (JJs) which can be realized as hybrids of superconducting (S) tunnel junction with a ferromagnetic inter-layer (F) on one side of the tunnel barrier (I), i.e. having SIFS structure. The magnetic film thickness determines the Josephson coupling and sets the phase coherence to either 0 or π.
SIFS multilayers consisting of Nb (140 nm)/Al (4)−Al2O3 (1)/CuNi (0−30)/Nb (40) were fabricated. The process parameters were derived from Josephson junctions with critical currents of about 0.1−1 kA cm2. The junction areas are ranged from 20.000 µ m2 down to 10 µ m2.
The first transport measurements of the junctions showed a monotonic decrease of IcRn for increasing FM-thickness. The generation of a semifluxon (cf. 1) pinned at the discontinuity of the magnetic layer thickness will be discussed. Since the semifluxon is a degenerated two state systems, it can be used as a qubit when the JJ is in the quantum limit.
[E. Goldobin et al., PRB 66, 100508 (2002)]