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  • Küçük Resim
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    Improvement of saturation magnetization of sputtered Fe/Al multilayer thin films using taguchi method supported by ANOVA, response surface methodology and regression analysis
    (Polska Akademia Nauk, 2023) Köçkar, Hakan; Kaplan, Nadir; Karpuz, Ali
    Taguchi method has been conducted to improve the saturation magnetisation, Ms, of Fe/Al multilayer thin films deposited using a dual-target magnetron sputtering. The Ms values were obtained from the magnetic hysteresis loops. To evaluate the influence of deposition factors on Msby using the Taguchi method, L9 orthogonal array with three deposition factors (A - Fe deposition rate, B - Al deposition rate, and C - Fe layer thickness) was carried out with nine experiments at three levels. For the signalto-noise ratio of the "larger is the better", the improved Mshas been obtained at A3B2C3, where factor A is 0.12 nm/s, factor B is 0.03 nm/s, and factor C is 25 nm. At A3B2C3, a verification experiment was carried out with a 95% confidence level to confirm the prediction of 1597.6 emu/cm3, and in the experimental run, Ms; expwas found to be 1649.0 emu/cm3, which was an improvement from the highest initial run, i.e., Ms; ini = 1540.2 emu/cm3, among prescribed runs. Analysis of variance was imposed to obtain the F-ratio and contribution percentage of each deposition factor. Also, the interactions of the deposition factors were determined with response surface methodology. For the structural properties at the best factor combinations, X-ray diffraction experiments revealed that Fe/Al films at A3B2C3 were crystallised with the mixed phase of face-centred cubic and body-centred cubic structures. According to scanning electron microscope images, the film surface is almost uniformly shaped. Furthermore, the model of Mshas also been developed using regression analysis as a function of the deposition factors A, B, and C. Then, from the regression model, high statistical performance was obtained, with values of R2and R2(adj) being 100 and 100%, respectively. It is seen that the Taguchi method supported by response surface methodology, analysis of variance, and regression analysis turned out to be very successful in finding the factors with proper levels in order to improve Msof Fe/Al multilayer thin fims within the prescribed limit.
  • Küçük Resim
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    Structural Properties Controlled Magnetisation of Ni/Al Multilayers Sputtered on Flexible Polymer Substrate: Impact of Ni Deposition Rates
    (Iop Publishing Ltd, 2024) Kaplan, Nadir; Karpuz, Ali; Köçkar, Hakan
    The goal of this work is to determine how the rate of Ni deposition rates affect the structural characteristics that regulate the magnetization of Ni/Al multilayer thin films sputtered on flexible acrylic acetate polymer substrates. The films with a 5[Ni(20 nm)/Al(10 nm)] structure were gradually sputtered as different Ni deposition rates in the total thickness of 150 nm. With an increase in the rate of Ni deposition, the Ni contents increased from 61.5% to 69.6%. And, X-ray diffraction analysis verified that the films featured a face-centered cubic structure with variable peak intensities. Also, the scanning electron microscopy surface morphology analyses revealed that variations in the film surfaces were a result of the deposition rates. For magnetic measurements, the differences in the structural analysis were observed to cause a notable variation in saturation magnetization, MS, and coercivity, HC values. Accordingly, MS values increased consistently between 359.0 and 389.7 emu cm-3, but HC values decreased from around 34-32 to 28 Oe with the increase in Ni deposition rate from 0.02 to 0.10 nm s-1. It is also observed that when the Ni layers are generated at very fast deposition rates, the Ni/Al multilayer films have a high MS/HC ratio, which is significant for magnetic sensors. It has been concluded that the magnetisation of Ni/Al multilayer thin films can be controlled by the structural properties adjusting the Ni deposition rate.