Creation of bulk, superlatticelike structure and giant magnetoresistance effect in a deformed Cu-Ni-Fe alloy

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Abstract
A spinodally decomposed Cu‐20 Ni‐20 Fe alloy containing ∼500 Å size ferromagnetic particles was uniaxially deformed to create a locally multilayered, superlatticelike structure with alternating ferromagnetic and nonmagnetic layers. When the size scale of each layer was made to be small, ∼15 Å thick, a dramatic improvement in room‐temperature magnetoresistance ratio from ∼0.6 to ∼5% was obtained. An abnormal temperature dependence of magnetoresistance ratio, i.e., the room‐temperature value being greater than that at 4.2 K, was found. The observed giant magnetoresistance behavior could be explained in terms of the field‐induced decrease in electron scattering in a nearly superparamagnetic material although the spin‐dependent scattering at the two‐phase interface and in the ferromagnetic phase may also be a contributing factor.