Browsing by Author "Koçkar, Hakan"

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2D Magnetic texture analysis of Co-Cu films
(Walter de Gruyter Gmbh, 2017-05-01) Bayırlı, Mehmet; Karaağaç, Öznur; Koçkar, Hakan; Alper, Mursel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The magnetic textures for the produced magnetic materials are important concepts in accordance with technical applications. Therefore, the aim of this article is to determine 2D magnetic textures of electrodeposited Co-Cu films by the measurement of hysteresis loops at the incremented angles. For that, Co-Cu films were deposited with different Co2+ in the electrolyte. In addition, the easy-axis orientation in the films from the squareness values of the angles, M-p(beta) obtained by the hysteresis loops have been numerically studied using the Fourier series analysis. The differences observed in the magnetic easy-axis distributions were attributed to changes of the incorporation of Co2+ in the films with the change of Co2+ in the electrolyte. The coefficients of Fourier series (A(0) and A(2n)) were also computed for 2D films. It is seen that a systematic and small decrease in A(0) and an obvious decrease in A(2n) (n = 1) were observed with increasing incorporated Co in the films. Results imply that interactions cause slightly demagnetization effect accordance with higher incorporation of Co in the films. Furthermore, the crystal structure of the Co-Cu films analysed by X-ray diffraction revealed that the films have dominantly face-centred cubic structure. Film contents analysed by energy-dispersive X-ray spectroscopy and film morphologies observed by scanning electron microscope also support the magnetic texture analysis results found by numerical computation.
A study on total thickness dependency: Microstructural, magnetoresistance and magnetic properties of electrochemically deposited permalloy based multilayers
(Springer, 2015-07-01) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; ALPER, MÜRSEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; AAG-8795-2021
Electrochemically deposited permalloy based NiFe/Cu multilayers, relating their magnetic and magnetoresistance properties with crystal structure and the corresponding film composition were studied as a function of the total film thickness. The permalloy based multilayers were grown on strong (110) textured copper sheets with electrodeposition under potentiostatic control. The total multilayer film thickness was changed from 0.3 to 5 mu m while ferromagnetic nickel-iron and nonmagnetic copper layer thickness was kept constant at 3 and 1 nm, respectively. Energy dispersive X-ray analysis revealed that the nickel and iron content of the multilayers decreased and copper content increased as the total film thickness increased. All multilayers exhibited face-centred cubic structure with (110) preferred orientation. The highest peak intensity changed from (220) to (111) when the total thickness was higher than 2 mu m. The multilayers exhibited giant magnetoresistance (GMR). The maximum GMR magnitude of similar to 4 % was obtained for the films with total thickness less than 1 mu m and the GMR decreased down to similar to 1 % with increasing film thickness to 5 mu m. The saturation magnetisation and coercivity decreased from 78 to 11 emu/cm 3 and from 24 to 12 Oe as the total thickness of the multilayers increased from 0.3 to 5 mu m, respectively. The variations in magnetic and magnetoresistive properties related to the microstructure were attributed to the variation of the film contents caused by total film thickness.
Change in planar hall effect ratio of Ni-Co films produced by electrodeposition
(Elsevier, 2015-01-01) Karpuz, Ali; Koçkar, Hakan; Alper, Mürsel; ALPER, MÜRSEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021
Ni-Co Films were produced by the electrodeposition technique and their magnetotransport properties were studied. The anisotropic magnetoresistance (AMR) and the planar Hall effect (PRE) ratios were Found using the van der Pauw setup at room temperature. It was observed that the ORE ratios were larger than the obtained AMR ratios. While the maximum changes in longitudinal and transversal magnetoresistance ratios were 6.8% and 140%, respectively, the change in ORE values was up to 500%. In the ORE measurements, the magnetoresistance orientation depends on the electrical resistance values which occur in branches of the films.
Characterisations of CoCu films electrodeposited at different cathode potentials
(Elsevier, 2010-05) Karaağaç, Öznur; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
Structural and magnetic properties of CoCu films electrodeposited on polycrystalline Cu substrates were investigated as a function of cathode potential used for their deposition. The compositional analysis, performed by energy dispersive X-ray spectroscopy, demonstrated that an increase in the deposition potential results in an increase in Co content of CoCu films. The crystal structure of the films was studied using the X-ray diffraction (XRD) technique. It was observed that they have a face centred cubic (fcc) structure, but also contain partly hexagonal close-packed phase. XRD results revealed that the (1 1 1) peak of fcc structure splits into two as Co (1 1 1) and Cu (1 1 1) peaks and the peak intensities change depending on the deposition potential and hence the film composition. The magnetic measurements were carried out at room temperature using a vibrating sample magnetometer. The magnetic findings indicated that coercivity decreases and saturation magnetisation increases with the increase of Co:Cu ratio caused by the deposition potential and also all films have planar magnetisation.
Characterisations of CoFeCu films: Influence of Fe concentration
(Elsevier, 2014-02-15) Koçkar, Hakan; Özergin, Ercüment; Karaağaç, Öznur; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The properties of electrodeposited CoFeCu films were studied with respect to Fe ion concentration in the electrolyte due to their interesting magnetic properties like high saturation magnetisation and low coercivity. The films were characterised in terms of microstructural and magnetic properties. From the compositional analysis, the Fe contents in the films are found to be consistent with the Fe ion concentrations in the electrolytes. With the surface morphology analysis of the films, the number of the roundish shape structures on the surface increased with increasing Fe ion concentration (>= 0.01 M Fe) whereas the CoCu films (0 M Fe) had ridged grains. The crystal structure of the films, examined by X-ray diffraction, changed from the mixed phase of the hexagonal close packed and face centered cubic (fcc) to the fcc and finally body centered cubic structure as the Fe ion concentration in the electrolyte increased from 0 to 0.04 M. And, the average grain size decreased with increasing Fe ion concentration. Magnetisation measurements by vibrating sample magnetometer displayed that the saturation magnetisation increased and the coercivity decreased as the Fe ion concentration increased. Also, it was found that the easy-axis of the magnetisation of films is parallel to the film plane. All films showed anisotropic magnetoresistance. The longitudinal and transverse magnetoresistance magnitudes of the films changed between 3.2-4.0 and 3.0-3.8, respectively. In the study, considerable differences in the microstructural and magnetic properties were observed and might be ascribed to the change of film content caused by the Fe ion concentration in the electrolyte. A high value of saturation magnetisation, M-s (1797 emu/cm(3)) is achieved under study.
Characterizations of electrodeposited NiCoFe ternary alloys: Influence of deposition potential
(Springer, 2015-06-01) Kuru, Hilal; Koçkar, Hakan; Demirbaş, Özen; Alper, Mürsel; ALPER, MÜRSEL; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021
Microstructural, magnetoresistance and magnetic properties of electrodeposited NiCoFe ternary alloys were investigated in terms of deposition potentials changing from -1.8 to -3.0 V with respect to saturated calomel electrode. The alloys were grown on polycrystalline Titanium substrates. The potentials were obtained from cyclic voltammetry and the current-time transients were also recorded to control the growth of proper alloys. From the structural analysis by X-ray diffraction, all alloys had a face-centred cubic structure. The alloy compositions by energy dispersive X-ray spectroscopy revealed that the Ni content increases whereas the Co and Fe contents decrease as the deposition potential increase. And, the scanning electron microscope images disclosed that the alloy morphologies changed as the deposition potential changed. All alloys showed anisotropic magnetic resistance and their magnitudes were between 4.5 and 8.7 %. The vibrating sample magnetometer measurements showed that the saturation magnetization of the alloys increases from 748 to 786 emu/cm(3) and coercivity decreases from 28.7 to 25.9 Oe as the deposition potential increases. The easy axis of magnetization was found to be parallel to the film plane for all alloys. The variations in magnetic and magnetoresistive properties related to the microstructure were attributed to the compositional changes caused by the deposition potential.
Characterizations of NiCu/Cu Multilayers: Dependence of Nonmagnetic Layer Thickness
(Springer, 2013-04) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; AAG-8795-2021; 7005719283
A series of NiCu/Cu multilayers were grown on (110) textured polycrystalline Cu substrates from a single electrolyte under potentiostatic deposition conditions. Microstructure, magnetoresistance and magnetic properties of the multilayers were investigated as a function of the nonmagnetic layer thicknesses. The structural studies by X-ray diffraction revealed that the multilayers have face-centered-cubic structure with preferred (110) crystal orientation as their substrates. The composition of the deposits determined by energy dispersive X-ray spectroscopy showed that the Cu content of the films increased as the Cu layer thickness increased. The scanning electron microscope studies showed that samples have homogeneous and smooth surfaces. Multilayers exhibited either anisotropic magnetoresistance (AMR) or giant magnetoresistance (GMR) depending on the non-magnetic Cu layer thickness. The multilayers with Cu layer thickness thicker than 0.7 nm exhibited GMR, but the AMR effect was observed to be dominant for the Cu layer thickness less than 0.7 nm. The GMR curves are broad in shape and the nonsaturated curves indicated the predominance of a superparamagnetic contribution. The GMR magnitudes of NiCu/Cu multilayers are found to be about 1-1.5 %. The vibrating sample magnetometer measurements revealed that the saturation magnetization decrease with increasing nonmagnetic layer thickness. The changes in the magnetic and magnetotransport properties might arise from the change in the Ni and Cu content of the samples caused by the variation of Cu layer thicknesses.
Co-Fe films: Effect of Fe content on their properties
(Amer Scientific Publishers, 2010-11) Koçkar, Hakan; Şahin, Turgut; Alper, Mürsel; Hacıismailoğlu, Mürşide Şafak; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAG-8795-2021; AAH-9719-2021; 37113797300; 36482867500
The characterizations of Co-Fe films electrodeposited on Ti substrates under potentiostatic conditions were investigated as a function of the Fe content in the films. The compositional analysis was carried out by energy dispersive X-ray spectroscopy. Scanning electron microscopy used to analyze the surface morphology of the films revealed that the film surface became rather smooth with the increase of the Fe contents. X-ray diffraction patterns showed that the crystal structure changed depending on the Co:Fe ratio in the films. It was observed that the crystal structure converted from the predominant face-centered-cubic to the body-centered-cubic with increasing Fe content. All films showed anisotropic magnetic resistance, but their magnitudes decrease as the Fe content increases. Magnetic data obtained from by vibrating sample magnetometer revealed that the changes observed in the saturation magnetization and coercivity values may arise from the Fe content of the films. The different magnetic and magnetotransport properties may come from the structural differences caused by the Fe content.
Comparison of Ni-Cu alloy films electrodeposited at low and high pH levels
(Elsevier Science, 2008-04-03) Koçkar, Hakan; Baykul, Mevlana Celalettin; Alper, Mürsel; Şafak, Mürside; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283; 13613646100
Ni-Cu alloy films were potentiostatically electrodeposited from the electrolytes with low pH (2.0) and high pH (3.3) levels. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD data showed that the crystal texture degree was different for the films grown at high pH and low pH. At high pH, the films have a strong (100) texture of the face-centred cubic (fcc) structure, while for the films at low pH the crystal planes are randomly oriented, as in a powder pattern of Cu (or Ni). The SEM studies revealed that the surface morphology of the films strongly depend on the electrolyte pH. Furthermore, the magnetic characteristics studied by a vibrating sample magnetometer (VSM) and magnetotransport properties were observed to be affected by the electrolyte pH. The differences observed in the magnetic and magnetotransport properties were attributed to the structural changes caused by the electrolyte pH.
Composition dependence of structural and magnetic properties of electrodeposited Co-Cu films
(IEEE, 2010-12) Karaağaç, Öznur; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The structural and magnetic properties of Co-Cu films were studied in terms of Co content in the films. The surface morphology of the films showed that the film with the lowest Co content (3 wt. %) had dendritic structures, whereas the surface of the film containing the highest amount of Co (61 wt. %) was more uniform with acicular shapes in some parts. X-ray diffraction patterns of the films showed that their crystal structure is a mixture of dominantly face-centered cubic (fcc) and hexagonal close-packed phases. At the lowest Co content, separate fcc (111) peaks appear, whereas the increase of Co content converts the peaks to be a single broad Co-Cu peak. The vibrating sample magnetometer measurements revealed that the saturation magnetization increases and coercivity decreases due to the decrease of the grain size caused by the increase of the Co content in the film. The structural and magnetic properties of Co-Cu films can be tailored, since these properties are directly related to the ratio of Co to Cu in the film.
Contribution of electrolyte pH and deposition potentials to the magnetic anisotropy of electrodeposited nickel films
(Elsevier, 2010) Koçkar, Hakan; Karaağaç, Öznur; Nakiboğlu, Nuri; Baykul, Mevlana Celalettin; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The influence of electrolyte pH and cathode potential on the magnetic properties of single layer Nickel films electrodeposited on polycrystalline titanium substrates was studied. The films were deposited at the electrolyte pH=3.5 +/- 0.1, 2.5 +/- 0.1 and 2.1 +/- 0.1 by varying the deposition potentials (-1.2, -1.5 and -1.8 V vs saturated calomel electrode, SCE) applied in continuous waveform. The structural analysis by X-ray diffraction revealed that the films have face-centred cubic structure. Results of the magnetic measurements obtained by vibrating sample magnetometer (VSM) indicated that the magnetic properties were affected by the electrolyte pH and the cathode potentials in terms of magnetic anisotropy. At the highest pH the films deposited at the lowest potential had in-plane magnetic anisotropy. As the electrolyte pH decreased from the high (pH=3.570.1) to low (pH=2.5 +/- 0.1), which is aided by increasing the potentials, resulted in an almost magnetic isotropy in the films. However, isotropic magnetic behaviour was observed for the film deposited at the low pH combined with the high potential (-1.8 V vs SCE). Magnetic thickness profile of the samples obtained by VSM revealed that the isotropic films have a smoother magnetic variation across the film from one edge than the anisotropic ones. This is also verified with a microscopic observation by an optical microscope and the surface of the isotropic films is observed to be smoother than that of the anisotropic ones. Furthermore, all films were found to have planar magnetic anisotropy irrespective of the pH's and the potentials
Dependence of magnetoresistance in electrodeposited CoNiCu/Cu multilayers on Ni composition
(Electrochemical SOC INC, 2010) Koçkar, Hakan; Myung, N.; Zangari, G.; PodlahaMurphy, L.; Hacıismailoğlu, Mürşide Şafak; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAG-8795-2021; AAH-9719-2021; 36482867500; 7005719283
A series of CoNiCu/Cu multilayers was potentiostatically electrodeposited on strong (100) textured Cu substrates from the electrolytes with different Ni concentrations. The x-ray diffraction (XRD) data showed that all studied samples exhibited a face centred cubic (fcc) structure. According to scanning electron microscopy (SEM) images, the surface morphology of the films is affected by their Ni content. The chemical analysis by energy dispersive x-ray spectroscopy (EDX) demonstrates that as the Ni ion concentration in the electrolyte is increased, the Ni content of the film increases while the Co and Cu contents decrease. Magnetoresistance (MR) measurements were carried out at room temperature in the magnetic fields of +/- 12 kOe. The samples grown from the electrolytes with the Ni concentration of up to 0.3 M exhibited giant magnetoresistance (GMR). For the samples grown from 0.3 M Ni, anisotropic magnetoresistance (AMR) begins to appear. The GMR decreased with increasing Ni concentration and the AMR appeared. For the 2.0 M Ni concentration, MR converted from GMR to AMR. Furthermore, the magnetization measurements made by a vibrating sample magnetometer (VSM) showed that the antiferromagnetic coupling between ferromagnetic layers weakened with increasing the Ni concentrations.
Determination of texture orientation related magnetic properties of nickel-cobalt films
(Walter De Gruyter, 2010-04) Bayırlı, Mehmet; Koçkar, Hakan; Çöktüren, Emrah; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The determination of texture effects in nickel-cobalt (Ni-Co) films with different thickness, which were obtained by electrodeposition, has been investigated by the measurement of hysteresis loops at different angles. Easy-axis distribution measurements were performed as a function of the squareness M-p(beta) and the correlations were established among the different thicknesses. The composition of Ni-Co films was determined by energy dispersive X-ray spectroscopy. The structural analysis made by X-ray diffraction revealed that all films have a polycrystalline face-centered cubic structure but their texture degrees vary depending on the film thickness. The determination of the easy-axis orientation in 2-D films from the M-p(beta) obtained by the hystersis loops was studied using Fourier series analyses. The coefficient A(0) have a value of less then unity while A(2) is inversely proportional to the width of the distribution function which may cause the change in the texture preferential orientations. Therefore, the differences observed in the magnetic easy-axis distributions were attributed to the changes in texture orientations caused by the compositional differences at different thicknesses of the polycrystalline films.
Development of electrodeposited multilayer coatings: A review of fabrication, microstructure, properties and applications
(Elsevier, 2021-08-12) Aliofkhazraei, M.; Walsh, Frank C.; Zangari, Giovanni; Koçkar, Hakan; Alper, Mürsel; Rizal, Conrad; Magagnin, Luca; Protsenko, Vyacheslav; Arunachalam, Ramanathan; Rezvanian, Amirreza; Moein, Arian; Assareh, Sahar; Allahyarzadeh, Mohammad Hossein; ALPER, MÜRSEL; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021
The demand for robust engineering materials demonstrating good tribological performance under arduous service conditions has forged the development of novel coating materials and techniques. In the field of surface engineering, multilayer structures have attracted great interest. Electrodeposition offers a versatile and controlled route to engineering coatings in tribology. Electrodeposited coatings can provide tailored electronic, magnetic, mechanical, wear-resistant and corrosion-resistant characteristics as well as an improved load-bearing capability. The performance of multilayered electrodeposits can significantly exceed that of single layers. This paper critically reviews the fabrication, microstructure, engineering properties and potential applications of electrodeposited multilayer coatings. Such coatings can provide powerful, complementary additions to the toolkit for engineering electrodeposition, enabling future advances. Critical aspects requiring further R & D endeavors are identified.
Differences observed in properties of ternary NiCoFe films electrodeposited at low and high pH
(Springer, 2013-06) Koçkar, Hakan; Demirbaş, Özen; Kuru, Hilal; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
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.
Effect of Co and Cu layer thicknesses on characterization of electrodeposited Co/Cu multilayers
(Amer Scientific Publishers, 2013-01) Koçkar, Hakan; Hacıismailoğlu, Mürşide Şafak; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; 0000-0001-5648-3230; AAG-8795-2021; AAH-9719-2021; 36482867500; 7005719283
Co/Cu multilayers were grown on polycrystalline Cu substrates from a single electrolyte by electrodeposition potentiostatically. The structural, magnetic and magnetoresistance (MR) properties of the multilayers were characterized according to both Co and Cu layer thicknesses. The structural analysis by X-ray diffraction (XRD) showed that all samples have face-centered cubic (fcc) structure with a strong (100) texture. Magnetic characterizations studied by vibrating sample magnetometer (VSM) revealed that the easy axes of the multilayers are parallel to the film plane. From magnetoresistance (MR) measurements, it was observed that all samples exhibited giant magnetoresistance (GMR). The GMR behavior of the multilayers changes depending on the thicknesses of both Co and Cu layers.
Effect of deposition potential and saccharin addition on structural, magnetic and magnetoresistance characteristics of nicofecu films
(Walter De Gruyter Gmbh, 2023-08-03) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; ALPER, MÜRSEL; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Psikoloji Bölümü.; 0000-0002-4862-0490
NiCoFeCu films were electrodeposited on Ti substrates at different deposition potentials and different concentrations of saccharin added to solution. Compositional analysis showed that although Ni was the highest concentration in solution at low potentials of - 1.0 V and - 1.5 V, the Ni content was lower than the Co content in the films. Anomalous co-deposition behaviour of iron group metals was observed. When the deposition potential increased to - 2.0 V and - 2.5 V, the Ni content of films increased while the Co, Fe and Cu content decreased. In the case of saccharin addition to the solution, there is a slight change in the film content. All films have face-centred cubic structure. Structural analysis clearly showed that the potential has a significant effect on the texture degree of the films, since the crystal texture changed from (111) to (220) with increasing potential. The surface morphology of the films was observed to be affected by the deposition potential and saccharin concentration. For the magnetic analysis, saturation magnetisation, M-s value gradually decreased from 905 to 715 emu/cm(3) with the variation of film content caused by the increase of the potential from -1.0 V to -2.5 V. And, a slight increase in M-s was detected with the addition of saccharin. Besides, the longitudinal and transverse magnetoresistance magnitudes increased from similar to 2.5 % to 7.0 % with increasing deposition potential and all films exhibit anisotropic magnetoresistance. Films with desired magnetic properties can be obtained for potential use as magnetic materials in electronics such as magnetoresistive devices.
The effect of different chemical compositions caused by the variation of deposition potential on properties of Ni-Co films
(Elsevier, 2011-02-01) Karpuz, Ali; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; AAG-8795-2021; 7005719283
The magnetic and microstructural properties of Ni-Co films electrodeposited at different cathode potentials were investigated. The compositional analysis revealed that the Ni content increases from 13 at.% to 44 at.% in the films with increasing deposition potential. Magnetic measurements showed that the saturation magnetization, M(s) of the films decreased with increase of Ni content as the deposition potential increased. Ms values changed between 1160 emu/cm(3) and 841 emu/cm(3). The X-ray diffraction revealed that the crystalline structure of the films is a mixture of the predominant face-centered cubic (fcc) and hexagonal closed packed. However, the mixture phase turns to the fcc because of increasing Ni content up to 44 at.% at the highest (-1.9 V) potential by enhancing the intensity of reflections from the fcc phase. The changes observed in the magnetic and microstructural properties were ascribed to the changes observed in the chemical composition caused by the applied different deposition potentials.
The effect of Fe content in electrodeposited CoFe/Cu multilayers on structural, magnetic and magnetoresistance characterizations
(Amer Scientific Publishers, 2010-11) Koçkar, Hakan; Karaağaç, Öznur; Tekgül, Atakan; Alper, Mürsel; Şafak, Mürşide; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; P-2124-2016; AAG-8795-2021; 37462175100; 7005719283; 13613646100
A series of CoFe/Cu multilayers were electrodeposited on Ti substrates from the electrolytes containing their metal ion under potentiostatic control, but the Fe concentration in the electrolytes was changed from 0.0125 M to 0.2 M. The deposition was carried out in a three-electrode cell at room temperature. The deposition of Cu layers was made at a cathode potential of -0.3 V with respect to saturated calomel electrode (SCE), while the ferromagnetic CoFe layers were deposited at -1.5 V versus SCE. 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 film plane. Magnetoresistance measurements were carried out using the Van der Pauw method at room temperature with magnetic fields up to +/- 12 kOe. All multilayers exhibited giant magnetoresistance (GMR) and the GMR values up to 8% were obtained.
Effect of film thickness on properties of electrodeposited Ni-Co films
(Elsevier, 2012-04-01) Karpuz, Ali; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
A series of Ni-Co films with different thicknesses was produced by using the electrodeposition technique and their microstructural, magnetic and magnetotransport properties were investigated. The X-ray (XRD) diffraction measurements showed that the films have the face centered cubic structure and the preferential orientations of the films were in the order of (1 1 1), (2 2 0) and (2 2 0) for the films with 1, 2 and 4 mu m thicknesses, respectively. The magnetic measurements revealed that the coercivity decreased from 52 Oe to 37 Oe due to the regular transition of preferential orientation from (1 1 1) to (2 2 0) with increasing film thickness. The study demonstrated that magnetic properties of the films changed according to the microstructural properties. Magnetoresistance investigations exhibited that all films have anisotropic magnetoresistance (AMR).