Hilal Kuru

Differences observed in properties of ternary NiCoFe films electrodeposited at low and high pH

Ternary NiCoFe films were potentiostatically electrodeposited from the electrolytes with low (3.0) and high (3.6) pH levels, and differences in their compositional, structural, magnetic and magnetoresistance properties were studied. The compositional analysis demonstrated that the Ni content in the films decreased, and Co and Fe content increased while electrolyte pH was changed from low to high level. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD data revealed that the films have a strong (111) texture of the face-centred cubic (fcc) structure at low pH, while for the films at high pH a mixture of dominantly fcc and hexagonal closed packed structure was observed. The SEM studies showed that films grown at low pH level had comparatively larger grains than those at high pH. The magnetic characteristics studied by a vibrating sample magnetometer and magnetotransport properties were seen to be changed by the electrolyte pH. However, all films have in-plane magnetic anisotropy. The differences observed in the magnetic and magnetotransport properties were attributed to the microstructural changes caused by the electrolyte pH.

Facile electrodeposition CoCu/Cu multilayers: deposition potentials for magnetic layers

The Co(Cu)/Cu magnetic multilayers were produced by electrodeposition technique as a function of the cathode potentials for magnetic layer deposition from a single bath. For proper depositions, cyclic voltammograms were used and the current–time transients were obtained. All potentials were determined with respect to saturated calomel electrode. The Co layers were deposited at cathode potentials of −1.3, −1.5 and −1.7 V, while −0.3 V was used for the Cu layers deposition. All multilayers were polycrystalline in the face-centred-cubic (fcc) structure with both Co and Cu layers adopting the fcc structure. The crystal structure of the multilayers is the same as fcc bulk Cu, but (220) peak splits the two peaks which are Cu(220) and Co(220). Both Co and Cu diffraction lines overlap in the (111) and (200) strong peaks and thus they seem to be a single peak. In the magnetisation measurements, the highest saturation magnetization was found to be 212 kA/m in producing with −1.5 V for Co deposition potential. The coercivities of multilayers are found to be 12.1, 16.9 and 18.3 kA/m for −1.3, −1.5 and −1.7 V cathode potentials, respectively.

Impact of Deposition Rate on the Structural and Magnetic Properties of Sputtered Ni/Cu Multilayer Thin Films

Abstract The structural and corresponding magnetic properties of Ni/Cu films sputtered at low and high deposition rates were investigated as there is a limited number of related studies in this field. 5[Ni(10 nm)/Cu(30 nm)] multilayer thin films were deposited using two DC sputtering sources at low (0.02 nm/s) and high (0.10 nm/s) deposition rates of Ni layers. A face centered cubic phase was detected for both films. The surface of the film sputtered at the low deposition rate has a lot of micro-grains distributed uniformly and with sizes from 0.1 to 0.4 μm. Also, it has a vertical acicular morphology. At high deposition rate, the number of micro-grains considerably decreased, and some of their sizes increased up to 1 μm. The surface of the Ni/Cu multilayer deposited at the low rate has a relatively more grainy and rugged structure, whereas the surface of the film deposited at the high rate has a relatively larger lateral size of surface grains with a relatively fine morphology. Saturation magnetisation, Ms, values were 90 and 138 emu/cm3 for deposition rates of 0.02 and 0.10 nm/s, respectively. Remanence, Mr, values were also found to be 48 and 71 emu/cm3 for the low and high deposition rates, respectively. The coercivity, Hc, values were 46 and 65 Oe for the low and high Ni deposition rates, respectively. The changes in the film surfaces provoked the changes in the Hc values. The Ms, Mr, and Hc values of the 5[Ni(10 nm)/Cu(30 nm)] films can be adjusted considering the surface morphologies and film contents caused by the different Ni deposition rates.