We have studied Josephson junctions with barriers prepared from the Heusler compound Cu2MnAl. In the as-prepared state the Cu2MnAl layers are non ferromagnetic and the critical Josephson current density jc decreases exponentially with the thickness of the Heusler layers dF . On annealing the junctions at 240 • C the Heusler layers develop ferromagnetic order and we observe a dependence jc(dF ) with jc strongly enhanced and weakly thickness dependent in the thickness range 7.0 nm < dF < 10.6 nm. We attribute this feature to a triplet component in the superconducting pairing function generated by the specific magnetization profile inside thin Cu2MnAl layers.

We studied superconducting V layers deposited on an antiferromagnetically coupled [Fe(2)V(11)](20) superlattice. The parallel upper critical magnetic field exhibits an anomalous T dependence up to the ferromagnetic saturation field of the superlattice, indicating that the superconducting transition temperature T(S) decreases when rotating the relative sublattice magnetization directions of the superlattice from antiparallel to parallel. This proves that the pair breaking effect of a Fe2 layer is reduced if at a distance of 1.5 nm a second Fe2 layer with antiparallel spin orientation exists.

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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 ξF 2 ≈ 0.79 nm between 0 and π-Josephson phase coupling and a very short decay length ξF 1 ≈ 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 .

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