Çift Katmanlı Demir Filmlerin Manyeto-Empedans Etkilerinin İncelenmesi

Cam zemin üzerinde manyetik çift katmanlı arasında manyetik olmayan bir tabaka kullanılarak (Fe/Cu/Fe) üretilen manyeto-empedans hücre (ME) elektron mikroskobu, X-ışını kırınımı, manyetik ve manyeto-empedans ölçümleri yapılarak incelenmiştir. ME etkisini gözlemlemek için frekansa bağlı empedans ölçümleri statik düşük manyetik alan altında yapılmıştır. Hücrelerin empedans değeri, 1 - 25 MHz frekans aralığında ve DC manyetik alanda (-25 - 25 Oe) sabit 4 mA AC akım kaynağı kullanılarak karakterize edilmiştir. Çift tepe tepkileri elde edilerek, ME etkisi % 35' e ve duyarlılığı 23.7 %/Oe' e kadar çıkartılmıştır. Gelecekteki sensör uygulamaları için bu malzeme, düşük fiyat aralığında ve kıyasla yüksek hassasiyet özelliklerine sahip dev manyeto-empedans etkisi gösterdiğinden dolayı umut verici bir aday haline getirilmiştir

The effect of heat treatment on the FeCo phase in Tb-Fe-Co thin films

Investigation of the magnetic behavior of nanostructured Tb-Fe-Co thin films before and after heat treatment below and above Fe-Co phase crystallization temperature has explored by electron microscopy (SEM), X-ray diffraction (XRD), temperature-dependent resistivity, magnetization (MOKE), magneto-resistivity, and Hall resistivity measurements. The thin films are composed of fine crystallites (from 10 to 75 nm) after heat treatment around the FeCo phase crystallization temperature obtained from XRD and SEM measurements. The nanostructured thin films show the unique perpendicular magnetic properties in the out-ofplane direction around the room temperature. The maximum squareness ratio value of as-deposited thin film with 10 nm crystallite size is 0.98, and the maximum coercive field value of 400 degrees C thin film with 60 nm crystallite size is 3897 Oe. Our findings offer a different perspective for synthesizing the nanostructured TbFe-Co thin films for promising applications in the magnetic sensor technologies. (C) 2020 Elsevier B.V. All rights reserved.Deutscher Akademischer Austausch Dienst (DAAD) 5731401

Entail the new path for permanent magnets: Free-standing Hf-Co thin films

Durak Yuzuak, Gizem/0000-0002-2358-8789WOS: 000376443300073In this work, as an alternative to permanent magnets containing rare earth, we report a method for the preparation of rare-earth-free (REF) free-standing magnetic thin films have been obtained by using a basis sacrificial layer with magnetron sputtering technique. Stoichiometric Hf34.5Co65.5 thin films are deposited on sacrificial layer coated on Si(100) substrate and removed by a selective wet-chemical etching method. Conditions for the crystallization of Hf2Co11 magnetic thin films are indicated. No crystalline peaks are found in the XRD pattern of the as-deposited film, remarking an amorphous structure. the formation of the hard magnetic orthorhombic Hf2Co11 phase requires a post-annealing at 773 K or higher until at 923 K. Freestanding Hf2Co11 thin film, which is post-annealed at 923 K, has following permanent magnet properties; H-c = 6 kOe, M-r = 370 emu.cm(-3), (BHi)(max) = 6.6 MGOe. (C) 2016 Elsevier B.V. All rights reserved.Ankara UniversityAnkara University [BAP 15L0443005]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This work was done at the Magnetic Materials Research Laboratory in Ankara University - Functional Materials Research Laboratory in Recep Tayyip Erdogan University and supported by Ankara University Research Funds (Grand Number: BAP 15L0443005). G.D.Y. would like to thank to TUBITAK for Ph.D. scholarship

Exploring the sputtering conditions in ZnO thin film for triboelectric nanogenerator electrode

The new field of applications for triboelectric materials is based on the combination of high physical durability and charge properties of ZnO semi-conductor thin films, which have been explored in this work. ZnO films are successfully deposited by the RF magnetron sputtering method in the wurtzite phase. A post-heat-treatment process of the as-deposited films is carried out in an oxygen atmosphere at 973 K. According to the X-ray diffraction patterns, scanning electron microscope (SEM), and atomic force microscopy (AFM) images, the average particle size of the ZnO films increases gradually with the heat-treatment process. The semilogarithmic current-voltage and frequency-dependent capacitance measurements of thin films under various bias voltages are done to understand the charge transfer resistance, conductivity and capacitance properties which directly affect the figure of merit (FOMm) of the triboelectric layer material performance. The charge density and triboelectric charge density values in present study for heat-treated thin films are 11 and 121 mC/m(2), respectively. These findings might be used as a good candidate for further triboelectric device energy research areas in the near future

Inverse magnetocaloric effect related to the magnetostructural phase transition in quaternary Ni-Co-Mn-Al alloy

The inverse magnetocaloric effect of Ni-Co-Mn-Al quaternary alloy with the relatively low material cost is achieved firstly in a theoretical study (V. Sokolovskiy et al.: J. Appl. Phys., 2020, vol. 127, p. 163901). To investigate and prove this study, the exact composition of Ni40Co10Mn36Al14 alloy is selected and and explored by the combination of X-ray diffraction, scanning electron microscopy, resistivity, and magnetic studies. The quaternary alloy reveals that the main phase is associated with a martensitic L1(0) phase structure with some austenitic B2 phase in the vicinity of room temperature. The results show that the alloy maintains both Austenite and Martensite phases and has a grand scale change in magnetization of approximately 95 emu g(-1) around the Martensitic phase transition (in the range of 20 K) that exhibits a first-order magnetic transition from ferromagnetic to non-ferromagnetic state. The alloy reveals the inverse magnetic entropy change of about 12 and 8 J kg(-1) K-1 and the relative cooling power of 125 and 76 J kg(-1) under only 15 and 10 kOe, respectively. Likewise, the MR value of 11.5 pct obtains in the external magnetic field source of 10 kOe in the heating direction. The experimental results support the referenced theoretical study and make this material prominent in future magnetocaloric and magnetoresistivity studies

Investigation of Magnetic Field Response Features of Multilayer CoFe onKapton Tape

Esnek bir alttaş (Kapton bant) üzerinde manyetik olmayan bir ara katman üzerinde üretilen ferromanyetik [Fe65Co35]5/Cu/[Fe65Co35]5 çok katmanlı manyeto-tepki hücreleri elektron mikroskobu, Xışını kırınımı, manyetik ve magneto empedans ölçümleri alınarak incelenmiştir. Benzer bir hücrede, bu katmanlar, seçilen büyüme altlığı sert bir yapıda olduğu zaman, olağanüstü bir magneto-empedans etki performansına sahip olduklarını göstermiştir. Burada, bu hücreler Kapton bant üzerinde büyütülerek, manyetik alan sensörü olarak kullanımı değerlendirilip ve magneto empedans özellikleri hazırlama koşulları açısından analiz edilmiştir. Gelecekteki algılama uygulamaları için bu malzeme, düşük fiyat aralığı ve nispeten yüksek hassasiyet özellikleri ile dev manyeto-empedans etkisi için umut verici bir adaydır. Manyeto empedans etkisini gözlemlemek için empedans ölçümlerinin frekans bağımlılığı, uygulanan düşük manyetik alanın bir fonksiyonu olarak gerçekleştirilmiştir. Hücrelerin empedans değeri, düşük frekans aralıklarında sabit 20 mA AC akım kaynağı ile karakterize edilmiştir. Si ve Kapton kaplamadaki filmde, duyarlılıkları, sırasıyla,% 30 / Oe ve% 17 / Oe civarında olan, manyeto empedans oranlarını % 140'a ve% 55'e kadar gösteren pik tepkileri elde edilmiştirMultilayer magneto-response cells (MMRC) fabricated on a non-magnetic layer among ferromagnetic [Fe65electron microscopy, X-ray diffraction, magnetic and magnetoimpedance measurements. In a similar cell, these layers have shown previously to have an outstanding magnetoimpedance (MI) effect performance when the selected growth substrate is a rigid one. Here, this MMRC produces on the Kapton tape and evaluate during the using as a magnetic field sensor and the magnetoimpedance characteristics are analyzed in terms of preparation conditions. For future sensing applications, this material is a promising candidate for giant magnetoimpedance effect with the range of low price and relatively high sensitivity features. In order to observe MI effect, the frequency dependence of impedance measurements has performed as a function of the applied low magnetic field. The impedance value of the cells has characterized by using constant 20 mA AC current source at low frequencies ranges. Double (out of plane measurement) peak responses have obtained, showing MI ratios up to % 140 and % 55, their sensitivities are around 30 %/Oe and 17 %/Oe in the film on Si and Kapton tape, respectivel

The magnetic and magnetocaloric properties of CoMnGe1-xGax alloys

Durak Yuzuak, Gizem/0000-0002-2358-8789; YUZUAK, ERCUMENT/0000-0001-6667-513XWOS: 000330179200054The magnetic and magnetocaloric properties of CoMnGe1 Ga-x(x) (0.02 <= x <= 0.063) alloys have been investigated by using calorimetric, X-ray diffraction and magnetic measurements. Our results show that the structural and magnetic phase transitions in CoMnGe1 Ga-x(x) alloys are tailored by the substitution of Ga for Ge. the CoMnGe1 Ga-x(x) (x = 0.05, 0.055 and 0.06) alloys exhibit a giant magnetocaloric effect due to coexistence of magnetic and Martensitic phase transitions at the same temperatures. the entropy change values range from -3.2 to -38.4 J kg (1) K (1) for Delta H = 7 T and are proportional to the volume differences of the phases involved in the transition. the adiabatic temperature change value of CoMnGe0.945Ga0.055 is calculated as 6.5 K for the magnetic field change of 2 T from magnetic and heat capacity measurements. the density of states of electrons at Fermi level and the Debye temperature values of this alloy are found 1.37 states eV (1) atom (1) and 337 K from low temperature heat capacity measurements. (C) 2013 Elsevier B. V. All rights reserved.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109T743]The authors would like to thank TUBITAK (Project Number: 109T743) for the financial support

Enhancing the power factor of p-type BiSbTe films via deposited with/without Cr seed layer

The thermoelectric effect is an efficient method to use waste heat as a primary source of electrical energy. Being a room temperature thermoelectric thin film, p-type BiSbTe is one of the best candidates owing to the combined high efficiency and large power factor for future technological applications. Novel approaches have emerged in recent decades with the aim of enhancing the thermoelectric properties of BiSbTe thin films. The method involves using Cr as an adhesion and seed layer for controlling microstructure and transport properties via the energy filtering of high-energy carriers. The heterostructure of Cr/BiSbTe film demonstrates the best electrical transport performance, where the Seebeck coefficient and the electrical conductivity are 425 mu V/K and 25 S/m* 10(3) in the vicinity of room temperature. The power factor of Cr/BiSbTe was reported to be 6.8 mW/mK(2) at 375 K, which was approximately seven times higher than the film without the Cr layer. We conclude that the inclusion of the Cr seed layer can notably improve the electrical transport properties of p-type BiSbTe films. (C) 2021 Elsevier B.V. All rights reserved

The magnetostructural and magnetocaloric properties of CoMnGe1-xGaxB0.015 (x=0.05 and 0.06) alloys

YUZUAK, ERCUMENT/0000-0001-6667-513X; Durak Yuzuak, Gizem/0000-0002-2358-8789WOS: 000329109300032The magnetostructural and magnetocaloric properties of CoMnGe1-xGaxB0.015 (x=0.05 and 0.06 are named Alloy-1 and Alloy-2, respectively) alloys have been investigated by X-ray powder diffraction, calorimetric and magnetization measurements. Both alloys have hexagonal structures at room temperature and show first order phase transition below room temperature. the entropy change-Delta S of these alloys are calculated as -22.1 J kg(-1) K-1 (for Alloy-1 alloy) and -27.1 J kg(-1) K-1 (for Alloy-2 alloy) under Delta H = 7 T. Magnetic hysteresis losses of these alloys are very small when compared with the undoped alloy. Considering the high magnetocaloric effect and low magnetic hysteresis features, boron doping on CoMnGe family alloys provides an alternative method to tailor magnetic and magnetocaloric properties. (C) 2013 Elsevier B.V. All rights reserved.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109T743]The authors would like to thank TUBITAK (Project no. 109T743) for the financial support

Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer

Yuzuak GD, Yuzuak E, Teichert N, Hütten A, Elerman Y. Thickness-Dependent Permanent Magnet Properties of ZrCo Thin Films Grown on Si with Pt Underlayer. METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE. 2017;48A(5):2654-2659.Zr-Co is one of the essential magnetic materials due to its interesting magnetic and structural properties. In this work, we studied the magnetic and structural properties of ZrCo thin films of different thicknesses grown on Si substrate with Pt underlayer. The structural properties and chemical composition of the ZrCo films were investigated by X-ray diffraction analysis, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analysis, and atomic force microscopy-magnetic force microscopy measurements. The saturation magnetization, M(H) characteristic, and Henkel plots of the Zr-Co films were obtained by vibrating-sample magnetometry. The results show that and were enhanced with decreasing layer thickness of Zr-Co. For 10-nm ZrCo with 20-nm Pt underlayer thin film, we observed coercive field of 2 kOe with energy product of 0.7 MGOe. Our results may be valuable for use of ZrCo thin films in nanomagnet applications