Effect of Ag addition on the magnetic and magnetoresistance properties of Fe53Pt47 films

A granular Fe53Pt47 film and two (Fe53Pt47)-Ag multilayers were prepared by rf sputtering on heated MgO (1 0 0) substrates. The samples were annealed in situ to induce a perpendicular anisotropy. The topography and magnetic domain structure are studied by AFM/MFM imaging. Magnetization loops are measured by alternating gradient magnetometry in directions perpendicular and parallel to the film plane from 5 K to room temperature. Magnetoresistance measurements are performed in the 2-300 K temperature interval by a standard four-contact method (maximum field: 70 kOe). Ag addition hinders the formation of the perpendicular phase. A negative magnetoresistance is observed in all samples, pointing to a spin-dependent scattering effect from FePt nanoparticles.