Planar SFS Josephson Junctions Made by Focused Ion Beam Etching

Abstract

Superconductor-Ferromagnet-Superconductor (S-F-S) Josephson junctions were fabricated by making a narrow cut through a S-F double layer using direct writing by Focused Ion Beam (FIB). Due to a high resolution (spot size smaller than 10 nm) of FIB, junctions with a small separation between superconducting electrodes ($\le$ 30 nm) can be made. Such a short distance is sufficient for achieving a considerable proximity coupling through a diluted CuNi ferromagnet. We have successfully fabricated and studied S-F-S (Nb-CuNi-Nb) and S-S'-S (Nb-Nb/CuNi-Nb) junctions. Junctions exhibit clear Fraunhofer modulation of the critical current as a function of magnetic field, indicating good uniformity of the cut. By changing the depth of the cut, junctions with the $I_c{R}_n$ product ranging from 0.5 mV to $\sim 1\mu$V were fabricated.

5 pages, 5 figures, presentation at EUCAS-2003, to be published in Physica C

References in corpus (3)

• Coupling of two superconductors through a ferromagnet : evidence for a pi-junction
• Oscillations of the superconducting critical current in Nb-Cu-Ni-Cu-Nb junctions
• Proximity Effect and Spontaneous Vortex Phase in Planar SF-Structures

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• Evidence for nonlocal electrodynamics in planar Josephson junctions
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• Mechanism of generation of a Josephson phase shift by an Abrikosov vortex
• Nonlocal long-range synchronization of planar Josephson junction arrays
• The physics of superconductor-ferromagnet hybrid structures
• Unusually strong coherent response from grain-boundary Josephson network in polycrystalline Pr_{x}Y_{1-x}Ba_2Cu_3O_7
• Planar Josephson junctions for sensors and electronics:Different geometry, new functionality
• Nonlinear standing waves on planar branched systems: Shrinking into metric graph