Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 11: Superconductivity: Tunneling, Josephson Junctions, SQUIDs
TT 11.3: Vortrag
Montag, 25. Februar 2008, 16:00–16:15, H 3010
Magnetic flux dynamics in 0, π and 0-π SIFS Josephson junctions — •Judith Pfeiffer1, Martin Weides2, Matthias Kemmler1, Alexey K. Feofanov3, Jürgen Lisenfeld3, Dieter Koelle1, Alexey V. Ustinov3, Reinhold Kleiner1, and Edward Goldobin1 — 1Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen, D-72076 Tübingen, Germany — 2Center of Nanoelectronic Systems for Information Technology (CNI), Research Centre Jülich, D-52425 Jülich, Germany — 3Physikalisches Institut III, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
We present experimental and numerical studies of high quality underdamped Superconductor-Insulator-Ferromagnet-Superconductor (SIFS) Josephson junctions fabricated as Nb/Al2O3/Cu40Ni60/Nb heterostructures. Varying the thickness of the ferromagnetic barrier one can fabricate 0, π and 0-π junctions. The dynamic and static properties of these junctions are studied by measuring the I-V characteristic and critical current Ic vs. magnetic field H. Using microwave spectroscopy we have investigated the eigenfrequencies of a 0, π and 0-π Josephson junction in the temperature range 4.2 K...300 mK. Harmonic, subharmonic and superharmonic pumping is observed in experiment and the experimental data are compared with numerical simulations. Perfoming thermal escape measurements at temperatures down to 300 mK we try to reach the quantum tunnelling regime.