Perpendicular barium ferrite ͑BaM͒ films with Pt interlayers were successfully fabricated. The magnetic and structural properties of BaM films were compared with BaM films without Pt interlayers. It was found that perpendicular c-axis orientation was greatly improved for films with Pt interlayers. Perpendicular remanent squareness is increased, and the c-axis dispersion angle ⌬ 50 is decreased with Pt interlayers in BaM films. Also the coercivity was found to increase for films with Pt interlayers. A relative increase in perpendicular nucleation sites over in-plane and/or random nucleation sites contributes to the improvement in perpendicular c-axis orientation. The increase in coercivity may be explained by a weakening of magnetostatic interactions among BaM grains, due to magnetostatic isolation by the nonmagnetic Pt interlayers and the interdiffusion between Pt layers and BaM layers during high temperature ex situ annealing.
The magnetic properties of CrPt 3 L1 2 ferrimagnetic thin films have been studied. Films were produced by sputtering multilayers of Cr and Pt onto silicon nitride coated silicon substrates. The as-deposited films are nonmagnetic. An anneal at ϳ800°C results in ferrimagnetic behavior with a perpendicular easy-axis. X-ray diffraction and transmission electron microscopy ͑TEM͒ measurements show that ͑111͒ CrPt 3 is the only crystalline phase present after annealing. Rocking curves with a full width at half maximum as low as 1.8°indicate good crystallographic orientation. Magnetic properties of the films vary with composition, annealing temperature and time, layer thickness, and sputtering conditions. The films exhibit large coercivities, H c , that can be tuned in the range 1500-8000 Oe. Saturation magnetization, M s , is typically 150-200 emu/cc. Squarenesses, S, as high as 0.99 have been found. A uniaxial magnetic anisotropy constant, K u , of up to 8ϫ10 6 erg/cc was achieved. TEM micrographs show a 35 nm average grain size and complete interdiffusion of the Cr and Pt. Magneto-optical hysteresis loops at 632.8 nm wavelength reveal Kerr rotations of about 0.21°when the films are overcoated with a quarter-wavelength dielectric.
The effects of stoichiometry factor on the magnetic and structural properties of perpendicular barium ferrite thin films with composition of BaO (Fe 2 O 3) were systematically investigated. Within the range 2 2 6, the-axis for barium ferrite thin films can be oriented perpendicularly by the use of Pt underlayer and with optimized processing conditions. Perpendicular-axis orientation becomes worse as decreases from 6 to 2.2. The average grain size was greatly reduced from about 2000 Å to 300 Å with the decrease of. The decrease of the grain size can be related to the existence of nonmagnetic phase BaFe 2 O 4 , which was observed by X-ray diffraction.
CoCrPt/Ti/Ag films with the easy axes of the hexagonal-closed-pack Co grains perpendicular to the film plane were epitaxially grown on HF-etched Si͑111͒ single crystal substrates by rf sputter deposition. The orientation relationship was determined by x-ray pole figure measurements and transmission electron microscopy to be CoCrPt͑0001͓͒1010͔ ʈ Ti͑0001͓͒1010͔ ʈ Ag͑111͓͒112͔ ϫ ʈ Si͑111͓͒112͔. The magnetic properties of the CoCrPt films were greatly improved by introducing these single crystal templates. Rocking curve measurement showed a greatly improved c-axis orientation of the cobalt alloy. Highly oriented, high coercivity properties for perpendicular recording have been obtained.
Barium ferrite thin films with perpendicular c-axis orientation and small grain size ͑about 300 Å͒ were successfully fabricated with careful control of sputtering conditions. The c-axis orientation of barium ferrite thin films is most sensitive to the oxygen partial pressure during deposition. All samples with oxygen gas during deposition have a random c-axis texture, as indicated by existence of both weak (00l) peaks and ͑106͒ peaks. All the samples without oxygen gas during deposition show only strong (00l) peaks, which indicate excellent perpendicular c-axis orientation. Transmission electron microscopy results show that oxygen gas promotes the growth of in-plane and/or randomly oriented grains. The effect of the Pt interlayer on the barium-rich films was also studied. The Pt interlayer was found to be very effective in improving c-axis orientation of barium-rich films. A relative increase in perpendicular nucleation sites over in-plane and/or random nucleation sites contributes to the improvement in perpendicular c-axis orientation.
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