Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 10: Superconductivity: Tunneling, Josephson Junctions, SQUIDs

TT 10.5: Vortrag

Montag, 23. März 2009, 15:15–15:30, HSZ 105

High frequency properties of Josephson π-junctions — •Georg Wild^1,2, Christian Probst¹, Achim Marx¹, and Rudolf Gross^1,2 — ¹Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Str. 8, 85748 Garching — ²Physik Department, Technische Universität München, Garching

Josephson junctions with ferromagnetic interlayer have attracted much interest due to their potential application as π-phase shift elements. We have developed a self-aligned multilayer process for the fabrication of superconductor/insulator/ferromagnet/superconductor Josephson junctions (S=Nb, I=AlO_x, F=NiPd). Our junctions have RCSJ-like current-voltage characteristics and a Fraunhofer diffraction pattern for the magnetic field dependence of the critical current. The dependence of the I_cR_n-product on the ferromagnet thickness shows a clear crossover from the zero- to the π-state. We have determined the plasma frequency of π-coupled junctions from Fiske resonances. This data is used to explain the different excitations found in microwave spectroscopy experiments at milli-Kelvin temperature.
This work was supported by the DFG via SFB 631 and the Excellence Initiative via NIM.