We have observed ‘‘giant magnetoresistance’’ in short-period Cu/Co-Ni-Cu alloy superlattices electrodeposited from a single electrolyte under potentiostatic control. The superlattices were grown on polycrystalline Cu substrates which were removed before transport measurements were made. Room-temperature magnetoresistances of over 15% in applied magnetic fields of up to 8 kOe were observed in superlattices having Cu layer thicknesses of less than 10 Å.

We have studied the effect of electrolyte pH on the “giant magnetoresistance” in Co‐Ni‐Cu/Cu superlattices prepared by electrodeposition. Films grown at low pH (1.8 ± 0.1) exhibited giant magnetoresistance (GMR) of over 15% while, depending on layer thicknesses, films grown at high pH (3.3 ± 0.1) exhibited either predominantly anisotropic magnetoresistance (AMR) or much smaller GMR than possible at low pH. Also, the films grown at low pH were found to have a higher magnetization than those grown at high pH. The different magnetic and magnetotransport properties observed for different values of the electrolyte pH are accompanied by changes in the shapes of the current transients recorded during film growth and by changes in the composition of the superlattices. A possible explanation of these results is that reducing the electrolyte pH leads to a more abrupt interface between the ferromagnetic and nonmagnetic layers by suppressing Co dissolution.

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We have electrodeposited a series of Co–Ni–Cu/Cu superlattices in which the Cu layer thickness was varied between 7 and 35 Å and the Co–Ni–Cu alloy layer thickness held constant. ‘‘Giant magnetoresistance’’ was observed for all films, with the magnitude of the effect decreasing with increasing Cu spacer layer thickness.

A series of CoFe/Cu multilayers were electrodeposited on Ti substrates from the electrolytes containing their metal ion under potentiostatic control, but the Fe concentration in the electrolytes was changed from 0.0125 M to 0.2 M. The deposition was carried out in a three-electrode cell at room temperature. The deposition of Cu layers was made at a cathode potential of -0.3 V with respect to saturated calomel electrode (SCE), while the ferromagnetic CoFe layers were deposited at -1.5 V versus SCE. The structural studies by X-ray diffraction revealed that the multilayers have face-centered-cubic structure. The magnetic characteristics of the films were investigated using a vibrating sample magnetometer and their easy-axis was found to be in film plane. Magnetoresistance measurements were carried out using the Van der Pauw method at room temperature with magnetic fields up to +/- 12 kOe. All multilayers exhibited giant magnetoresistance (GMR) and the GMR values up to 8% were obtained.

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