AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI-FrM

Paper MI-FrM4
Corrosion Behavior of CoSm Based Magnetic Media

Friday, October 6, 2000, 9:20 am, Room 206

Session: Magnetic Recording: Media and Heads
Presenter: I. Zana, The University of Alabama
Authors: I. Zana, The University of Alabama
G. Zangari, The University of Alabama
Correspondent: Click to Email
Future state-of the-art magnetic recording media require high coercivity and magnetization and from a low noise stand point, a small grain size. To achieve these properties, alloys and compounds with high anisotropy are being considered. Among them, we previously reported on rare-earth transition metal CoSm thin films@foontote 1@ with very good magnetic properties. Despite these attractive magnetic properties, the potentially high susceptibility to corrosion, due particularly to the rare-earth element, rises the question of chemical stability for these alloys and therefore on the practicality of CoSm system. In order to investigate the chemical stability of a CoSm system, we fabricated a series of samples on glass substrates, by sputtering. To evaluate the influence of the roughness of both underlayer and magnetic layer, we sputter Cr as underlayer with thickness of 20, 60 and 100 nm. Onto each Cr underlayer, the magnetic layer has a thickness of 8 and 16 nm. These samples were further coated, without breaking the vacuum, with a protective layer of C-N and Si3N4 (2 to 8 nm thickness). A series of samples has been left intentionally unprotected. Corrosion resistance of the samples has been tested by high temperature /humidity accelerated aging and annealing under various atmospheres. Structural and chemical uniformity, roughness as well as stability of the magnetic properties of aged samples have been evaluated by use of x-ray photoelectron spectroscopy, electron microscopy, x-ray diffraction and magnetometry. By comparison with unprotected samples and with commercial disk structure, we found that (a) Si3N4 protective layer strongly improve the corrosion resistance and stability of the magnetic layer and (b) CoSm layers protected by Si3N4 exhibit stability comparable or superior to commercial hard disk. @FootnoteText@@footnote 1@I. Zana, G. Zangari, "Magnetic Interactions and Thermal Stability in CoSm Thin Films", accepted to publication in IEEE Transactions on Magnetics.