Nanostructured contiguous networks of Fe well suited to fundamental studies of the effects of confinement are described. The Fe networks are prepared by sputter deposition onto the surface of nanochannel alumina. One of the most obvious consequences of confining the magnetic material to a nanostructured network is a dramatic enhancement in the coercivity when compared to a continuous Fe film of the same thickness.

Films of Fe, Co, and Co35Fe65 alloy have been sputter deposited onto the surface of porous nanochannel alumina substrates producing nanostructured contiguous magnetic “networks.” Large room temperature coercivities have been measured which approximately scale with the bulk saturation magnetization of the material used. In the as-deposited state the largest coercivities (e.g., >1000 Oe for Co35Fe65) are observed in ∼15-nm-thick networks deposited on the smallest commercially available pore size substrates (those having an average pore diameter of ∼20 nm and a wall thickness of ∼15 nm). Preliminary studies of the effects of annealing indicate that coercivities can be substantially increased (by as much as ∼50%) with an appropriate post-deposition thermal treatment.

Giant magnetoresistance (GMR) has been observed in Ni,,Fe,,Co,$Cu multilayered uniaxial magnetic thin films prepared by dc magnetron sputtering. Both easy and hard axis loops saturate at very low applied fields. The MR ratio reaches -80% of its saturation value in less than 30 Oe. A maximum MR ratio of -10% has been observed in the as-deposited state in a structure containing only ten bilayers. Typical hysteresis values for magnetoresistance loops are -4 Oe in the as-deposited state. A gradual decrease of this hysteresis has been observed with annealing. An increase in the saturation field is also observed with annealing. Short-term annealing increases the magnitude of the magnetoresistance ratio; prolonged annealing causes a decrease. A field sensitivity of about 0.3% per Oe has been observed and dc magnetoresistance minor loops exhibit no measurable decrease in sensitivity.

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