Evolution from multilayer to granular behavior via Cobalt layers fragmentation in Co/Cu multilayers

• Published in: Journal of magnetism and magnetic materials Vol. 262; no. 1; pp. 120 - 123
• Main Authors: Vavassori, P, Spizzo, F, Angeli, E, Bisero, D, Ronconi, F
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2003; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diamagnetism, paramagnetism and superparamagnetism; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Fine-particle systems; Giant magnetoresistance; Granular films; Magnetic properties and materials; Magnetization curves, hysteresis, Barkhausen and related effects; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Magnetotransport phenomena, materials for magnetotransport; Metals and alloys; Multilayers; Physics; Small particles and nanoscale materials; Sputtering; Studies of specific magnetic materials; Superparamagnetism; 75.20.−g; Multilayers; 75.47.−m; 75.50.Tt; Superparamagnetism; Giant magnetoresistance; 75.47.De; Granular films; Sputtering; Temperature dependence; Particle size; Magnetization; 75.20. g; Experimental study; Cobalt; Fragmentation; Thickness; Spin diffusion; Transition elements; Coercive force; 75.47.-m; Copper; 75.47.De Superparmagnetism
• ISSN: 0304-8853
• DOI: 10.1016/S0304-8853(03)00032-5

We have analyzed the structural evolution of Co(tCo)/Cu(4tCo) multilayers when tCo ranges from 12 to 2Å. The investigation has been performed by studying their magnetization (both at room and low temperatures) and giant magnetoresistance. In the intermediate range of thickness, we observe mixed multilayer granular features yielding an interesting behavior of magnetoresistance curves related to the length scale of the spin-dependent scattering processes. At sufficiently low Co thickness, the samples exhibit non-interacting superparamagnetic behavior (at room temperature). The analysis of the low-temperature data (coercive field and of the ratio between the remnant and saturation magnetization) of the superparamagnetic samples allowed us to address the effects related to particles size distribution on the temperature dependence of coercive field and of the ratio between the remnant and saturation magnetization.