Browsing by Author "Kockar, Hakan"

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    Influence of deposition parameters of Novel Vacuum Coating Plant on evaporated Ni60Fe40 and Ni80Fe20 films
    (Amer Scientific Publishers, 2009-06) Kockar, Hakan; Williams, Paul; Karaağaç, Öznur; Meydan, Turgut; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
    The aim of this study is to deposit and then characterize a large quantity of magnetic materials and understand how the Novel Vacuum Coating Plant (VCP) system affects the properties of the materials. Ni60Fe40 and Ni80Fe20 were the compositions chosen for the investigation. The films were deposited on rigid and flexible substrates using the novel VCP. Data from Inductively Coupled Plasma Atomic Emission Spectrometry analysis performed on the source alloys confirmed that element concentrations were within 0.3% of the compositions. The X-ray diffraction patterns indicated that all films have face-centred cubic structure. Ni60Fe40 films evaporated on a polyimide (kapton (TM)) substrate showed anisotropic behaviour due to the flexible nature of the substrate, aided by the relatively high magnellostriction caused by the composition, whereas the films produced on glass substrates exhibit only isotropic magnetisation irrespective of their compositions. Observations indicate that in-plane anisotropy and coercivity is dependent on the type of substrates and the compositions. All films showed planar magnetic anisotropy. It is seen that large film areas can be produced and their properties were affected by the deposition parameters in the VCP system.
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    Substrate type and their rotation speed controlled magnetic anisotropy of iron films evaporated by a newly designed vacuum coating system
    (Natl Inst Optoelectronics, 2014-03) Kockar, Hakan; Karaağaç, Öznur; Kuru, Hilal; Karpuz, Ali; Hacıismailoğlu, Mürşide S.; Alper, Mürsel; Akkaya, Cengiz; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; AAH-9719-2021; AAG-8795-2021; 36482867500; 7005719283; 14061855100
    A newly designed Vacuum Coating System (VCS) system has been used for the first time to prepare magnetic iron thin films on plastic kapton and rigid glass substrates at different rotation speeds (0 rpm, 30 rpm, 60 rpm, and 90 rpm). The powdered iron as a source material was evaporated by a resistively heated furnace positioned right under the substrate within the VCS system. Magnetic measurements showed that an in-plane magnetic anisotropy exist in all films. The films deposited on flexible kapton show that the degree of uniaxial magnetic anisotropy and coercivity decreased with decreasing rotational speed. For glass substrates used at low speeds (0 rpm and 50 rpm) magnetic isotropy was observed and coercivity was found to be almost constant while a slight anisotropy and a small change of coercivity was observed at 90 rpm. Coercivity of the films deposited on kapton substrates was found to be higher than that of the films on glass substrates. The estimation of in-plane uniaxial anisotropy was obtained from the hysteresis loops of the films confirmed the experimental in-plane magnetic anisotropy findings. Observations indicate that the uniaxial in-plane magnetic anisotropy and coercivity are dependent on the type of substrate and their rotation speeds.
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    The effect of ferromagnetic and non-ferromagnetic layer thicknesses on the electrodeposited CoFe/Cu multilayers
    (Springer, 2015-04) Kockar, Hakan; Tekgül, Atakan; Alper, Mürsel; Haciismailoğlu, Mürşide; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; 0000-0001-8220-6851; 0000-0001-5648-3230; P-2124-2016; AAG-8795-2021; AAH-9719-2021; 37462175100; 7005719283; 36482867500
    A series of CoFe/Cu multilayer was electrodeposited as a function of ferromagnetic and non- ferromagnetic layer thicknesses on Ti substrates from a single electrolyte containing Co (from CoSO4), Fe (from FeSO4), Cu (from CuSO4) metal ions under potentiostatic control. The deposition was carried out in a three electrode cell at room temperature. The Cu and CoFe layers were deposited at a cathode potential of -0.3 and -1.5 V with respect to saturated calomel electrode respectively. 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 the film plane. Magnetoresistance measurements were carried out at room temperature with magnetic fields up to +/- 955 kA/m using the Van der Pauw method. All multilayers exhibited giant magnetoresistance (GMR). The GMR values up to 22 % and a GMR sensitivity of 52 % per 1 kA/m were obtained.