GRANULAR GIANT MAGNETORESISTANCE AT LOW FIELDS IN BILAYER THIN-FILMS

Granular giant magnetoresistance is observed at saturation fields of 350-1100 Oe in thin-film structures consisting of a discontinuous layer of Co or NiFe deposited on an insulating substrate and overcoated with Cu. The phenomena are similar to that recently observed in codeposited immiscible alloys such as Co-Cu, although at lower fields. The bilayer structure does not require immiscibility and thus allows a greater materials choice. Magnetoresistance values up to 3% are observed and the reduced saturation fields are attributed to the controlled size and shape of the ferromagnetic islands.