Josephson junctions incorporating a conical magnetic holmium interlayer

Josephson junctions incorporating a conical magnetic spacer layer of Ho were measured as a function of spacer layer thickness and an applied magnetic field. The characteristic voltage decreased as a function of layer thickness without the obvious presence of any pi phase shifts, although the decay was somewhat fragmented. The decay is exponential with a decay coherence length of xi(f) approximate to 4.34 nm and the Ho mean-free path is calculated to be l(Ho) = 0.28-0.87 nm, which suggests the system is in the dirty limit. The dependence of the junction critical current on the magnetic field is nonmonotonic with interlayer thickness, but is explicable in terms of the Ho long-wavelength magnetic structure.