NANOSTRUCTURAL EFFECTS AND INTERFACE MAGNETISM IN CO/PD MULTILAYERS

A series of Co/Pd multilayers were made by dc magnetron sputter deposition on Al foil substrates. For these multilayered samples, Co layer thicknesses were less than 4 angstrom and Pd layers were varied from 4 to 22 angstrom. Sputtering rates were controlled by either sputtering power (10-50 W) or Ar sputtering pressure (3-15 mTorr). In both cases, lower deposition rates yielded higher perpendicular coercivity up to 2.6 kOe. Structures of the samples were studied using conventional theta-2theta x-ray diffractometry (XRD). It has been found that magnetic properties such as coercivity and saturation magnetization are sensitive to interfacial structures. A nanostructural model including interfacial parameters such as alloy layer composition is discussed and compared with the magnetization data. Both XRD and magnetization measurements show that the interfaces become more diffuse at higher sputtering pressures.