Design and structural characterization of perpendicular magnetic superlattices

Abstract

Various perpendicular ferromagnetic superlattices of the Co/Pd system were made to tune magnetic properties and recording performance, dependent on factors like sputtering pressure, sputtering gas, bilayer number, sublayer thickness, deposition temperature, annealing, type of seed layer, seed layer thickness and grain size, and distribution. Structural analysis by x-ray diffraction and TEM shows columnar growth and orthorhombic (tetragonal) microcrystalline packing that accounts for the ferromagnetic properties by polarization of the atoms during deposition, in contrast to the non-ferromagnetic state of the fcc crystal structure superlattice after high-temperature annealing. The M-H loop is described by a recently developed analytical hysteresis model and the result is substantiated by the structural analysis of grain sizes from multiple magnetic phases.