Browsing by Author "Kuru, Hilal"

Now showing 1 - 20 of 20

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.
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.
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 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.
Effect of NiFe layer thickness on properties of NiFe/Cu superlattices electrodeposited on titanium substrate
(Springer, 2019-10-01) Kuru, Hilal; Aytekin, Nuray Çolak; Koçkar, Hakan; Hacıismailoglu, Muerside; Alper, Mürsel; Hacıismailoğlu, Muerside; Alper, Mürsel; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAG-8795-2021; AAH-9719-2021
NiFe/Cu superlattices having different ferromagnetic NiFe layer thicknesses were grown on polycrystalline titanium substrate from a solution containing nickel, iron and copper ions under potentiostatic control. The NiFe layer thickness of the superlattices was changed from 1.5 to 8 nm while the Cu layer thickness was kept constant at 1 nm. The energy dispersive X-ray analysis revealed that, as the NiFe layer thickness increases, the Ni content of the samples increases, the Cu content decreases and Fe content decreases slightly. NiFe/Cu superlattices were polycrystalline face centred cubic (fcc) structure with NiFe and Cu layers adopting the fcc structure due to the low amount of Fe content in the deposits. The crystal orientation of the superlattices was obtained as {111}. The lattice parameters were calculated and slightly decrease from 0.36012 to 0.35382 nm with increase in the NiFe layer thickness. According to the Scanning Electron Microscopy images, when the NiFe layer thickness increases, the cauliflower region becomes less and then the granular-like regions were seen on the surface of the samples. And, the magnetic measurements showed that the saturation magnetization gradually increased from 12.9 to 291.3 emu/cm(3) with increasing NiFe layer thickness from 1.5 to 8 nm, confirming the increase of the Ni contents and decrease of the Cu amount in the superlattices. Also, the coercivities ranging from 25.1 to 63.2 Oe are between the soft and hard magnetic properties. The superlattices having NiFe layer thickness less than 5 nm showed giant magnetoresistance (GMR) while the superlattices having greater NiFe layer thicknesses showed aniotropic magnetoresistance. The GMR values of up to 2% were observed for NiFe/Cu superlattices deposited on titanium substrate. It is seen that this material may have the potential applications in sensor and recording media.
Electrochemical deposition of CoCu/Cu multilayers: Structural and magnetic properties as a function of non-magnetic layer thickness
(Walter de Gruyter, 2018-02) Koçkar, Hakan; Kuru, Hilal; Tekgül, Atakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; P-2124-2016; AAG-8795-2021; 37462175100; 7005719283
Electrochemical deposition of CoCu/Cu multilayers was performed on titanium substrates from a single bath as a function of the Cu layer thicknesses. The deposition potentials were selected as -1.5 V for the magnetic layers and -0.3 V for the non-magnetic layers with respect to the saturated calomel electrode. The current-time transients were obtained during the deposition process, and the Co layer deposition and capacitive transients were calculated. On the basis of structural analysis, the multilayers were found to be polycrystalline with both Co and Cu layers adopting the face-centered cubic structure. The calculated lattice parameters of the multilayers slightly increase from 0.3585 to 0.3615 nm with increase in the Cu layer thickness, which is consistent with the bulk value of Cu. The inter-planar distance of the peaks of the multilayers is closer to that of Cu (d(111) = 0.2087 nm) and Co (d(111) = 0.2046 nm), and they become close to that of bulk Cu with increasing Cu layer thickness. In magnetic measurements, the magnetization decreases from 156 to 44 emu/cm(3) depending on the Cu layer thickness. Furthermore, the coercivity of the multilayers increases from 20 to 140 Oe. These values show that the magnetic behaviour of the multilayers lie between those of soft and hard magnetic materials, but the multilayer having 2.5 nm Cu layer thickness shows hard magnetic property. For the CoCu(4 nm)/Cu(0.7 nm) multilayer, the magnetoresistance measurement shows 5.5 % giant magnetoresistance (GMR).
Electrochemical, structural and magnetic analysis of electrodeposited CoCu/Cu multilayers: Influence of Cu layer deposition potential
(Springer, 2018-03) Koçkar, Hakan; Kuru, Hilal; Ünlü, Cumhur Gökhan; Tekgül, Atakan; Alper, Mursel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; P-2124-2016; AAG-8795-2021; 37462175100; 7005719283
The electrochemical, structural and magnetic properties of CoCu/Cu multilayers electrodeposited at different cathode potentials were investigated from a single bath. The Cu layer deposition potentials were selected as , and with respect to saturated calomel electrode (SCE) while the Co layer deposition potential was constant at versus SCE. For the electrochemical analysis, the current-time transients were obtained. The amount of noble non-magnetic (Cu) metal materials decreased with the increase of deposition potentials due to anomalous codeposition. Further, current-time transient curves for the Co layer deposition and capacitance were calculated. In the structural analysis, the multilayers were found to be polycrystalline with both Co and Cu layers adopting the face-centered cubic structure. The (111) peak shifts towards higher angle with the increase of the deposition potentials. Also, the lattice parameters of the multilayers decrease from 0.3669 nm to 0.3610 nm with the increase of the deposition potentials from to , which corresponds to the bulk values of Cu and Co, respectively. The electrochemical and structural results demonstrate that the amount of Co atoms increased and the Cu atoms decreased in the layers with the increase of deposition potentials due to anomalous codeposition. For magnetic measurements, the saturation magnetizations, obtained from the magnetic curves of the multilayers were obtained as 212 kA/m, 276 kA/m, and 366 kA/m with , , and versus SCE, respectively. It is seen that the values increased with the increase of the deposition potentials confirming the increase of the Co atoms and decrease of the Cu amount. The results of electrochemical and structural analysis show that the deposition potentials of non-magnetic layers plays important role on the amount of magnetic and non-magnetic materials in the layers and thus on the magnetic properties of the multilayers.
Electrodeposited CoFeCu films at high and low ph levels: Structural and magnetic properties
(Springer, 2015-04-01) Koçkar, Hakan; Özergin, Ercüment; Karaağaç, Öznur; Alper, Mürsel; Kuru, Hilal; Hacıismailoğlu, Mürside; ALPER, MÜRSEL; ŞAFAK HACIİSMAİLOĞLU, MÜRŞİDE; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAH-9719-2021; AAG-8795-2021
CoFeCu films were electrodeposited at high and low pH, and their structural, magnetic and magnetoresistance properties were studied. Current-time transients were recorded to observe the proper deposition of the films. Crystal structure was displayed with X-ray diffraction. All films had a face centered cubic structure and the crystal structure was dominated by fcc-Co. The morphology and elemental composition of the films were determined by scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. The surface of the film deposited at low pH has larger roundish shapes than that of the film deposited at high pH. The saturation magnetization increases from 1,210 to 1,413 emu/cm(3) and coercivity increases from 29 to 39 Oe as the electrolyte pH increases. All CoFeCu films showed anisotropic magnetoresistance. It is seen that electrolyte pH has an substantial affect on the morphological and magnetic properties of the films.
Electrodeposited NiCoFe films from electrolytes with different Fe ion concentrations
(Elsevier, 2014-06) Koçkar, Hakan; Demirbaş, Özen; Kuru, Hilal; Karaağaç, Öznur; Özergin, Ercüment; Hacıismailoğlu, Mürşide S.; Alper, Mürsel; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAH-9719-2021; AAG-8795-2021; 36482867500; 7005719283
Ternary NiCoFe films, relating their magnetic and magnetoresistance properties with film composition, and the corresponding crystal structure were investigated in terms of different Fe ion concentrations in the electrolyte. The current-time transients were recorded to control the growth of proper films. The film composition by energy dispersive X-ray spectroscopy revealed that as the Fe ion concentration in the electrolyte was increased, the Fe and Co contents in the films increased and Ni content decreased. From the structural analysis by X-ray diffraction, all films had a face-centred cubic structure and, no reflection from body-centred cubic (bcc) Fe was existed in all samples due to < 12 at% Fe. The saturation magnetisation increased from 865 emu/cm(3) to 1080 emu/cm3 and the coercivities decreased from 60 Oe to 13 Oe with increasing Fe and Co contents and decreasing Ni content in the films. All NiCoFe films showed anisotropic magneforesistance. The longitudinal magneforesistance magnitudes decreased from 6.3% to 2.2% with increasing Fe and Co contents and decreasing Ni in the films while the magnitudes of trans-verse magneforesistance stayed almost constant at similar to 5.0%. The variations in magnetic and magneforesistive properties related to the crystal structure were attributed to the compositional changes caused by the variation of the Fe ion concentration in the electrolyw.
Electrodeposited NiFeCu/Cu multilayers: Effect of Fe ion concentration on properties
(Elsevier, 2015-03-01) Kuru, Hilal; Koçkar, Hakan; Alper, Mursel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-8220-6851; AAG-8795-2021; 7005719283
A series of 125[NiFeCu(3 nm)/Cu(1 nm)] multilayers were electrodeposited on strong (110) textured Cu substrates from electrolytes containing different Fe ion concentrations under potentiostatic control. The compositional analysis by energy dispersive X-ray spectroscopy demonstrated that as the Fe ion concentration in the electrolyte is increased, the Fe content of the multilayers increased. X-ray diffraction measurements indicated that all samples exhibited a face-centred cubic structure with a strong (110) texture as their substrates. The surface images obtained by scanning electron microscopy disclosed that all films have smooth surfaces. Magnetoresistance measurements were carried out at room temperature with magnetic fields up to +/- 12 kOe. All samples exhibited giant magnetoresistance (GMR) and the maximum GMR value of 5% was obtained in the multilayer grown from the electrolyte containing 0.0036 M Fe ion concentration. The GMR magnitude changed depending on the film contents arising from the variation of the Fe ion concentration in the electrolyte. The magnetic properties studied with the vibrating sample magnetometer showed that the saturation magnetisation changed, and the coercivities decreased with varying Fe ion concentration in the electrolyte. The changes observed in the properties were ascribed to the variations observed in the film composition caused by the Fe ion concentration of the electrolyte.
Facile electrodeposition CoCu/Cu multilayers: Deposition potentials for magnetic layers
(Springer, 2016-11-18) Koçkar, Hakan; Kuru, Hilal; Tekgül, Atakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-6737-3838; P-2124-2016; 37462175100; 7005719283
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.
Giant magnetoresistance (GMR) behavior of electrodeposited NiFe/Cu multilayers: Dependence of non-magnetic and magnetic layer thicknesses
(Elsevier, 2017-12-15) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyet Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
Giant magnetoresistance (GMR) behavior in electrodeposited NiFe/Cu multilayers was investigated as a function of non-magnetic (Cu) and ferromagnetic (NiFe) layer thicknesses, respectively. Prior to the GMR analysis, structural and magnetic analyses of the multilayers were also studied. The elemental analysis of the multilayers indicated that the Cu and Ni content in the multilayers increase with increasing Cu and NiFe layer thickness, respectively. The structural studies by X-ray diffraction revealed that all multilayers have face centred cubic structure with preferred (1 1 0) crystal orientation as their substrates. The magnetic properties studied with the vibrating sample magnetometer showed that the magnetizations of the samples are significantly affected by the layer thicknesses. Saturation magnetisation, M-s increases from 45 to 225 emu/cm(3) with increasing NiFe layer thickness. The increase in the Ni content of the multilayers with a small Fe content causes an increase in the Ms. And, the coercivities ranging from 2 to 24 Oe are between the soft and hard magnetic properties. Also, the magnetic easy axis of the multilayers was found to be in the film plane. Magnetoresistance measurements showed that all multilayers exhibited the GMR behavior. The GMR magnitude increases with increasing Cu layer thickness and reaches its maximum value of 10% at the Cu layer thickness of 1 nm, then it decreases. And similarly, the GMR magnitude increases and reaches highest value of pure GMR (10%) for the NiFe layer thickness of 3 nm, and beyond this point GMR decreases with increasing NiFe layer thickness. Some small component of the anisotropic magnetoresistance was also observed at thin Cu and thick NiFe layer thicknesses. It is seen that the highest GMR values up to 10% were obtained in electrodeposited NiFe/Cu multilayers up to now. The structural, magnetic and magnetoresistance properties of the NiFe/Cu were reported via the variations of the thicknesses of Cu and NiFe layers with stressing the role of layer thicknesses on the high GMR behavior.
Growth of binary Ni-Fe films: Characterisations at low and high potential levels
(Elsevier, 2015-03-01) Kuru, Hilal; Koçkar, Hakan; Karaağaç, Oznur; Alper, Mürsel; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-8220-6851; AAG-8795-2021; 7005719283
Binary Ni-Fe films relating their magnetoresistance and magnetic properties with crystal structure and surface morphology, and the Corresponding film composition were investigated at low and high deposition potentials. Based on the results obtained horn a cyclic voltammetry curve, a potential region between -1.3 V and -1.8 V was selected, and the current-time transients were recorded to control the proper film growth. The Ni-Fe films were potentiostatically electrodeposited on polycrystalline titanium substrates at low (-1.3 V) and high (-1.8 V) deposition potential. The data from the energy dispersive X-ray spectrometry and the inductively coupled plasma atomic emission spectroscopy demonstrated that the Ni and Fe content in the films varied as the potential changed. The magnetotransport properties and magnetic characteristics studied by a vibrating sample magnetometer (VSM) were observed to be affected by the deposition potentials. All films were also noted to exhibit anisotropic magnetoresistance behaviour. At low potential, the magnitude of the longitudinal magnetoresistance (LMR) was high (3.93%) and that of the transverse magnetoresistance (TMR) was low (3.49%) while for the film at high potential the LMR (2.76%) and the TMR (3.66%) magnitudes were obtained. Magnetization measurements by VSM revealed that the saturation magnetization, M-s was 779 emu/cm(3) and saturation field, H-s was 142 Oe at low potential while for the films deposited at high potential the M-s and H-s were 749 emu/cm(3) and 262 Oe, respectively. However, the coercivities in the films were found to be around 4.5 Oe, regardless of the potential. Also, the magnetic easy axis was found to be in the film plane for all samples. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. To XRD analysis, all films have a strong (111) texture of face-centred cubic structure and the lattice parameters, d-spacings and average grain size slightly changed with deposition potential. The films studied by SEM revealed that they have smaller grains grown at low deposition potential compared to those deposited at high potential. The differences observed in the properties of the films might be attributed to the compositional changes caused by the deposition potential.
Influence of deposition potentials applied in continuous and pulse waveforms on magnetic properties of electrodeposited nickel-iron films
(Elsevier Science Sa, 2006-05-24) Koçkar, Hakan; Kuru, Hilal; Meydan, Turgut; Alper, Mürsel; Uludağ Üniversitesi/Fen Edebiyet Fakültesi/Fizik Bölümü.; AAG-8795-2021
The effect of the various cathode potentials applied in continuous and pulse waveforms on magnetic anisotropy of NiFe alloy films grown on (100) textured polycrystalline copper substrates has been studied. Magnetic measurements obtained by a vibrating sample magnetometer (VSM) showed that the magnetic anisotropy of the films is very sensitive to the cathode potentials and the type of the potentials applied during deposition. It was found that the easy axis of all films is in the film plane. The magnetic findings also indicated that the NiFe films deposited at the cathode potentials of - 1.2 and - 1.5 V applied in the continuous waveforms, but except for the films deposited at the cathode potential of - 1.8 V, are anisotropic, while those produced at the cathode potentials applied in the pulse waveform show an isotropic magnetic behaviour. Utilising the magnetic properties of the films may offer the potential for the development of a new range of stress sensors. (c) 2005 Elsevier B.V. All rights reserved.
Magnetic anisotropy and its thickness dependence for NiFe alloy films electrodeposited on polycrystalline Cu substrates
(Elsevier, 2006) Koçkar, Hakan; Kuru, Hilal; Meydan, Turgut; Alper, Mürsel; Uludağ Üniversitesi/Fen Edebiyet Fakültesi/Fizik Bölümü.; AAG-8795-2021; 7005719283
The thickness dependence of magnetic properties of NiFe alloys electrodeposited on polycrystalline copper substrates has been investigated. In order to see how the film thickness affects their properties, the films with various thicknesses were deposited by keeping the cathode potential at -1.5V vs. the saturated calomel reference electrode (SCE). Magnetic measurements show that the magnetic properties are very sensitive to the film thicknesses and, the easy axis of all films is in the film plane. The results showed that the 1 and 2 mu m thick NiFe films are anisotropic and the degree of their anisotropy depends on film thickness whereas those deposited at the thickness of 3 mu m show an isotropic magnetic behaviour. It is also found that the increase of the nickel content when increasing their thickness results in an increase in the coercivity values.
Properties of electrodeposited CoFeNi/Cu superlattices: The effect of CoFeNi and Cu layers thicknesses
(Springer, 2013-04) Koçkar, Hakan; Karaağaç, Öznur; Kuru, Hilal; Kalsen, Sonser; Alper, Mürsel; Hacıismailoğlu, ‪Mürşide; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAH-9719-2021; AAG-8795-2021; 55537933800; 7005719283; 36482867500
CoFeNi/Cu superlattices were grown on Ti substrate by electrodeposition as a function of the ferromagnetic and non-magnetic layer thicknesses. In order to examine the effect of the Cu layer thickness on the film properties, the Cu layer thickness was changed from 0.5 to 6 nm, while the CoFeNi layer thickness was kept constant at 4 nm. Also, for the CoFeNi layer effect, the CoFeNi layer thickness was changed from 2 to 15 nm, while the Cu layer thickness was fixed at 4 nm. The structural analysis studied by X-ray diffraction indicated that the superlattices have face-centered-cubic structure. Magnetic characteristics were investigated by vibrating sample magnetometer. From the hysteresis curves, the coercivity and the saturation magnetization were determined. It was found that the easy-axis of the films is parallel to the film plane. Magnetoresistance measurements were made by the Van der Pauw method at the room temperature with magnetic fields up to +/- 12 kOe. All superlattices exhibited giant magnetoresistance (GMR). As the ferromagnetic layer thickness increased up to 4 nm, the GMR value increases up to 22 % and then decreases. The superlattices saturated at the lower magnetic layers with increasing ferromagnetic layer thickness. The maximum GMR value was obtained to be 22 % for a superlattice with 375[CoFeNi(4 nm)/Cu(4 nm)].
Relation between ferromagnetic layer thickness (NiCu) and properties of NiCu/Cu multilayers
(Springer, 2015-03-27) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; Hacıismailoğlu, Mürşide; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAH-9719-2021; AAG-8795-2021; 7005719283; 36482867500
NiCu/Cu multilayers were grown on (110) textured polycrystalline Cu substrates from a single electrolyte containing Ni and Cu ions by electrodeposition. The structural, magnetic and magnetoresistance properties of the NiCu/Cu multilayers were investigated as a function of the ferromagnetic layer thickness. The ferromagnetic NiCu layer thickness of the multilayers was varied from 2 to 10 nm while the nonmagnetic Cu layer thickness was fixed at 1 nm. Energy dispersive X-ray analysis revealed that the Ni content of the films increased and Cu content decreased as the NiCu layer thickness increased. Multilayers have the face centred cubic structure with (220) preferred orientation as their substrates. Also, the highest peak intensity changed from (220) to (111) with increasing NiCu layer thickness. The saturation magnetization, M-s and the coercivity, H-c of the samples was significantly affected by the film compositions that were varied by the ferromagnetic layer thicknesses. The M-s was increased from 36 to 239 emu/cm(3) and the H-c increased from 6 to 94 Oe with increasing ferromagnetic layer thickness. The multilayers exhibited either giant magnetoresistance (GMR) or the anisotropic magnetoresistance (AMR) depending on the NiCu layer thickness. The maximum GMR magnitude of 1.5 % was obtained for the films with 4 nm NiCu layer thickness. The MR measurements indicated that the films with the NiCu layer thickness up to <= 4 nm exhibited the GMR effect whereas for the films with 5 nm NiCu thickness the AMR effect appeared, and then the amount of GMR conversion to AMR effect increased as the NiCu layer thickness in the films increased from 5 to 10 nm. Thus, the variation in microstructure of the multilayers and corresponding magnetisation and magnetoresistance changes may arises from the NiCu layer thickness.
Relation between ferromagnetic layer thickness (NiCu) and properties of NiCu/Cu multilayers (vol 26, pg 5014, 2015)
(Springer, 2015-07-01) Kuru, Hilal; Koçkar, Hakan; Alper, Mürsel; Hacıismailoğlu, Mürşide; ALPER, MÜRSEL; ŞAFAK HACIİSMAİLOĞLU, MÜRŞİDE; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0001-5648-3230; AAH-9719-2021; AAG-8795-2021
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.