Low-temperature magnetic softening by competing anisotropy compensation in a granular FePt-Ag multilayer

A multilayered nanogranular film of nominal composition (Fe53Pt47)28Ag72 was deposited by RF sputtering on a MgO(1 0 0) substrate. The sample was annealed in situ to induce a perpendicular anisotropy. Magnetization loops were measured by alternating gradient magnetometry in directions perpendicular and parallel to the film plane from 5 K to room temperature. Magnetoresistance measurements were performed in the 2-300 K temperature interval by a standard four-contact method (maximum field: 70 kOe). A negative giant magnetoresistance is observed at all temperatures; below 11.5 K a strong positive effect adds, which is ascribed to anisotropic magnetoresistance