Josephson tunnel junctions with ferromagnetic Fe0.75Co0.25 barriers

• Published in: Journal of physics. D, Applied physics Vol. 42; no. 7; pp. 075005 - 075005 (5)
• Main Authors: Sprungmann, D, Westerholt, K, Zabel, H, Weides, M, Kohlstedt, H
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.04.2009; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Proximity effects, weak links, tunneling phenomena, and josephson effects, adreev effect, sn and sns junctions; Superconductivity; Vortex lattices ,flux pinning, flux creep; Ultrathin films; Aluminium oxide; Magnetic flux; Pair breaking; Oscillations; Aluminium; Magnetically soft alloy; Niobium; Magnetic tunnel junction; Thickness; Flux pinning; Magnetic scattering; Josephson effect; Transition elements; High field; Tunnel junction; Cobalt alloys; Exchange interactions; Iron base alloys; Transition element alloys
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/42/7/075005

Josephson tunnel junctions with the strong ferromagnetic alloy Fe0.75Co0.25 as the barrier material were studied. The junctions were prepared with high quality down to a thickness range of a few monolayers of Fe-Co. An oscillation length of xiF2 0.79 nm between 0 and pi-Josephson phase coupling and a very short decay length xiF1 0.22 nm for the amplitude of the superconducting pair wave function in the Fe-Co layer were determined. The rapid damping of the pair wave function inside the Fe-Co layer is caused by the strong ferromagnetic exchange field and additional magnetic pair breaking scattering. Josephson junctions with Fe-Co barriers show a significantly increased tendency towards magnetic remanence and flux trapping for larger thicknesses dF.