Controllable Josephson current through a pseudospin-valve structure

Abstract

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 (IC) is observed at 4.2 K, in addition to a magnetoresistance (MR) of ∼0.5% at high bias. The hysteresis loop of the spin-valve structure can be cycled to modulate the zero field IC of the junction in line with the MR measurements. These modulations of resistance and IC 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 IC modulation.