Surfactant-Assisted Growth of Giant Magnetoresistive Magnetic Multilayers

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9731733 Chopra This is a study of NiO-Co-Cu-based "giant" magnetoresistive magnetic multilayers in spin valve configuration, deposited by dc-magnetron sputtering. The goal is to employ surfactants to control elementary film deposition steps at the atomic level in order to modify the nature of interfaces and film morphology. This approach should result in basic understanding of the structure sensitivity of the magneto- transport properties in these layered systems. Deposition of a suitable number of layers of a surfactant on a given layer of a multilayer should alter the balance between surface and interface energies. The potential surfactant species (Ag, As, Sn, Sb, and Pb) are soft metals having large atomic volumes, properties that favor their "floating" out to the surface during over-layer growth and leaving behind intact layers with smooth interfaces less prone to intermixing. Surfactant assisted evolution of surface topography with respect to surfactant-free spin valves is studied at different stages of film growth in-situ and ex- situ (using scanning tunneling microscopy and atomic force microscopy). Surface segregation of surfactants is monitored by X-ray photoelectron spectroscopy. Magnetic properties, domain structures and wall transition in applied field are measured. %%% Artificially modulated magnetic multilayers comprised of magnetic and non-magnetic films are the subjects of intense research. These systems have potential device applications as magneto-optical storage materials using multilayers with perpendicular anisotropy and as next-generation read-heads for high-density storage. ***