Yazar "Kockar, Hakan" seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Evaluation of properties of sputtered Ni/Cu films with different thicknesses of the Cu layer(Elsevier, 2021) Çölmekçi, Salih; Karpuz, Ali; Kockar, HakanIn this study, Ni/Cu thin films with Cu layer thicknesses varying from 200 nm to absence of Cu (0 nm) were produced by using a magnetron sputtering technique in order to investigate their structural and magnetic properties. The X-ray diffraction analysis showed that the films deposited had a face-centered cubic structure and their crystallization was preferably oriented at the (111) plane. In addition, as the Cu layer thickness decreased from 200 nm to 0 nm, the intensity of fundamental Cu (111) decreased while the intensities of Ni (111) and Ni (200) increased. According to surface analysis, although pure Cu film had some specific and clear structures that were nearly spherical in form and varied in size on the surface, the film with a Cu layer thickness of 90 nm had some dark spots on the surface. The saturation magnetization (Ms) values increased with the increase of the Ni content of the films as the Cu layer thicknesses gradually decreased. Conversely, while the Cu content reduced with decreasing Cu layer thicknesses, the coercivity (Hc) values also decreased, except for the film with Cu layers thickness of 90 nm. It is possible that the dark spots seen in the scanning electron microscope image may have lowered the Hc value for the film with a Cu layer thickness of 90 nm. Thus, the production parameters of the film with a Cu layer thickness of 90 nm are optimal for obtaining multilayer films with a lower Hc value. Also, the parameters of the Ni/Cu multilayers with a Cu layer thickness of 15 nm can be considered to achieve a relatively high Ms value. In conclusion, changes in the Cu layer thickness can lead to significant alterations in the microstructural and therefore the magnetic properties.Öğe Investigation of the effects of Cu layer thickness and annealing temperature under air atmosphere on the properties of Co/Cu multilayer films(Iop Publishing Ltd, 2023) Karpuz, Ali; Kockar, Hakan; Kaplan, NadirIn this study, the suitability of Co/Cu multilayer films with different physical conditions (varying thickness values and systematic annealing processes) in magnetic technology applications is discussed. Co/Cu films were deposited by the sputtering technique. The effects of different thicknesses of non-magnetic (Cu) layers and annealing temperature on magneto-structural properties were investigated. Different thicknesses of Cu layers were determined as 34 nm, 10 nm, 4 nm. Additionally, two annealed situations were considered to investigate the annealing effect. While the first one is exposing the films to 80 & DEG;C and 130 & DEG;C for 240 s, second one is annealing the films at 180 & DEG;C for different exposure times (50 s and 150 s). All films that have different thicknesses of Cu layers crystallized in (111) plane of the face centered cubic (fcc) structure. The intensity of this peak increased with increasing Cu layers thickness. Variation in the thickness of Cu layers has an important effect on the film surface. Saturation magnetization (Ms), coercivity (Hc) and squareness (Mr/Ms, Mr: remanent magnetization) were considerably affected by variation of the Cu content and film surface caused by the change in the thickness of the Cu layers. The film with 4 nm Cu layer thickness has the highest Ms, lowest Hc values and high Mr/Ms ratio. This indicates magnetically high efficient compared to the other films in the same series. The fcc structure continued to exist for the films annealed at 80 & DEG;C and 130 & DEG;C for 240 s. It was found that the annealing procedure transfigured the film surface and the differences in Ms and Hc values can be mostly attributed to this transfiguration because of the same film content revealed. An increase in Ms value, and a slight decrease in Hc and Mr/Ms values were detected for the annealed film at 130 & DEG;C, compared to the film annealed at 80 & DEG;C. It was also seen that the film structure was damaged at 180 & DEG;C because of excessive heat transfer.Öğe Magnetic properties affected by structural properties of sputtered Ni/Cu multilayer films with different thicknesses of Ni layers(Springer, 2022) Çölmekçi, Salih; Karpuz, Ali; Kockar, HakanNickel-containing magnetic films have become the focus of attention due to their outstanding properties. These films are produced by many methods, including the sputtering technique. In this study, structural and magnetic properties of Ni/Cu multilayer films with different (from 92.5 nm to 17.5 nm) thicknesses of the Ni layers were investigated. The magnetron sputtering process was used to produce the Ni/Cu multilayer films. X-ray diffraction analysis showed that the films have a face-centered cubic structure with (111) plane. According to the scanning electron microscope images, while the films with the Ni layers thicknesses of 92.5 nm and 42.5 nm have some cracks and row structures on their surfaces, the films with lower thicknesses of the Ni layers have relatively more regular surfaces. As the Ni layers thickness decreased, the saturation magnetization (Ms) decreased from 617 emu/cm3 to 387 emu/cm3. Although the Ni/Cu multilayer with the Ni layer thickness of 92.5 nm had the highest atomic Ni content (76%); its coercivity (Hc) value was also the highest with 144 Oe. There was a decrease in the Hc value and grain size with decreasing the Ni layer thickness and the change in the Hc value can be related to the film content and surface morphology. The remanent magnetization (Mr) value changed between 492 emu/cm3 and 105 emu/cm3 with the reducing the Ni layers thickness. The highest Mr value and the highest Mr/Ms ratio were obtained for the Ni/Cu film with the Ni layers thickness of 42.5 nm. This Ni/Cu film has also the highest magnetization energy. The detected magnetic properties make this film desirable for permanent magnet and magnetic recording applications among the investigated Ni/Cu multilayers.Öğe Parametric characterizations of sputtered fe/al multilayer thin films(Springer Verlag, 2020) Karpuz, Ali; Kockar, Hakan; Colmekci, Salih; Uckun, MehmetThis study contains parametric characterizations of four different series of Fe/Al multilayer thin films sputtered under thicknesses of Al layers (7.5, 35 and 95 nm), deposition rates (0.02 and 0.06 nm/s), Fe layer thicknesses (7.5, 12.5 and 27.5 nm) and total thicknesses (100, 125 and 175 nm), separately. The X-ray diffraction measurements showed that all films have a mixture of face-centered cubic (fcc) and body-centered cubic (bcc) phase. The face-centered cubic (fcc) and mostly body-centered cubic (bcc) phase turned to the mostly fcc and bcc phase as the thickness of Al layer increased. On the other hand, the intensity of peaks belongs to bcc structure increased and mostly bcc structure was detected when the deposition rate increased. The roughness on the surfaces of Fe/Al multilayer increased as Al layer thickness decreased and deposition rate of layers increased. Saturation magnetization value changed coherently with the film content for all films. Coercivity, H-c value was significantly affected by different surface morphologies, and granular surface caused higher H-c values for Fe/Al multilayer thin films. It was found that crystalline structure, surface properties and magnetic properties of Fe/Al multilayer thin films depend strongly on the deposition parameters.
