| NiFe-based spin valves with large magnetoresistance and small driving field are very promising magnetic flux sensor materials for future ultra high density recording because of the high signal output and high field sensitivity. In this thesis, a comprehensive study has been made of the transport and magnetic properties of four different NiFe-based spin valve multilayer structures, i.e. Cu/Co/Cu/NiFe, FeMn/NiFe/Co/Cu/CoNiFe, NiFe/Co/Cu/Co/NiFe/NiO, and FeMn/NiFe/Co/Cu/Co/NiFe/Co/Cu/Co/NiFe/NiO. The multilayers used in this investigation were prepared by sequential deposition using a sputtering technique. The transport properties of these films were characterized by resistivity, anisotropic magnetoresistance, and giant magnetoresistance.In addition to the spin valve multilayers, the unidirectional anisotropies of permalloy thin films exchange-coupled to rf-reactive sputtered nickel monoxide films are analyzed. Studies were made on bilayered ferromagnetic Ni81Fe19/antiferromagnetic NiO films as a function of layers thicknesses. For a 100A thick Ni81Fe19 film deposited on top of a 400A thick NiO film, an exchange anisotropy field of 115 Oe was obtained at room temperature after the samples were field-cooled from 200°C. The equivalent interfacial exchange coupling energy is 0.09 ergs/cm2. |
