EFFECT OF SPUTTERING PRESSURE ON THE STRUCTURE AND CURRENT-PERPENDICULAR-TO-THE-PLANE MAGNETOTRANSPORT OF CO AG MULTILAYERED FILMS/

Co/Ag multilayers have been sputter-deposited at pressures ranging fro m 0.86 to 10 mTorr, and magnetotransport measurements have been perfor med with the current both perpendicular to the plane (CPP) and in the plane (CTP) of the samples. X-ray-scattering studies indicate that the roughness of the interfaces is influenced by the presence of the Nb l ayers used to make electrical contact for the CPP measurements, as wel l as by the sputtering pressure. For samples deposited at higher sputt ering pressures, the Nb contact layers also influence the low-temperat ure coercive field of the multilayers. The CPP-giant magnetoresistance is observed to decrease with increasing sputtering pressure and, in t he case of the signal observed after cycling to above the saturation f ield, this decrease is found to come in roughly equal measure from an increase in the high field-saturated specific resistance and a decreas e in the field-dependent specific resistance. Making use of the direct connection between microscopic physical parameters and experimental r esults available through the CPP geometry, we show that both of these changes arise primarily from increased scattering in both spin channel s. We see very little, if any, evidence for a change in the spin-depen dent scattering with sputtering pressure.