Magnetic Properties of Nano-Heterogeneous Amorphous Thin Films

We report continued progress in understanding the nanostructure-magnetic property relationships in sputtered, amorphous, thin films. This research has been concentrated on two categories of sputtered magnetic thin films; (1) magnetically soft films, of cobalt-based, binary (cobalt-metalloid) alloys with in plane anisotropies, and (2) magnetically hard, binary (rare earth metal-transition metal) alloy films with perpendicular anisotropies. Major research results obtained include: (1) development of the first broadband measurement technique and apparatus for determining the complex permeability spectra of magnetic thin films in the 100KHz-200MHz frequency range; (2) processing of magnetically soft amorphous thin films with the highest values of RF permeabilities ever reported in the literature; (3) discovery of a new class of ultrasoft magnetic thin films with coercivities less than 0.1 Oe and completely reversible bias susceptibilities; (4) systematically studied the microstructure, magnetic and magneto-optic properties of Tb-Fe and Gd-Co compositionally modulated films; (4) demonstrated that substrate bias could be used to increase the oxidation resistance and improve the magnetic and magnetooptical properties of sputtered Tb-Fe CMFs; and (5) developed a model of displacement eddy currents to resolve a long standing mystery about the origin of eddy current losses in magnetic recording head laminates.