Controllable Josephson current through a pseudospin-valve structure

A thin Co/Cu/permalloy (Ni80Fe20) pseudospin-valve structure is sandwiched between superconducting Nb contacts. When the current is passed perpendicular to the plane of the film a Josephson critical current (I-C) is observed at 4.2 K, in addition to a magnetoresistance (MR) of similar to0.5% at high bias. The hysteresis loop of the spin-valve structure can be cycled to modulate the zero field I-C of the junction in line with the MR measurements. These modulations of resistance and I-C occur both smoothly and sharply with the field applied. For each type of behavior there is a strong correlation between the shape of the MR loops and the I-C modulation. (C) 2004 American Institute of Physics.