FMR Study of Co/Ti Bilayer Thin Films

. We focused on the interaction between two ferromagnetic cobalt layers through a non-magnetic titanium layer. The magnetic properties of the structure were characterized by ferromagnetic resonance technique (FMR). The data were collected as a function of non-magnetic titanium layer thickness. Co/Ti multilayer (Ti (50 {\AA})/Co(45 {\AA})/Ti(2-40 {\AA})/Co(40 {\AA})/Ti(100 {\AA}))films were grown onto naturally oxidized p-type single crystal Si (100) substrate at UHV condition with magnetron sputtering system at room temperature. The thickness of Ti spacer layer ranges from 2 to 40 {\AA} with 2 {\AA} steps. We did not observe usual optic and acoustic modes; instead we had two broad overlapped peaks for the films ranged from 6 {\AA} to 40 {\AA}. One interesting result was the high anisotropic resonance field values for these films. Exchange coupling between ferromagnetic layers causes shift on resonance field values but these shifts in our samples were much larger than expected. This large anisotropic behavior is not clear at the moment. Our theoretical model was not able to determine a value for the exchange coupling parameter. One reason can be the close thickness values for Co sublayers. The other reason can be the Ti non-magnetic layer. If titanium did not grow layer by layer on cobalt, the cobalt ferromagnetic layers may behave as a single layer. As a result one cannot observe exchange interaction between ferromagnetic layers through non-magnetic spacer.Comment: 6 pages, 5 figure

Probing antiferromagnetism in NiMn/Ni/(Co)/Cu3Au(001) single-crystalline epitaxial thin films

Antiferromagnetism of equi-atomic single-crystalline NiMn thin film alloys grown on Ni/Cu3Au (001) is probed by means of magneto-optical Kerr effect (MOKE). Thickness-dependent coercivity (HC) enhancement of polar MOKE measurements in NiMn/Ni/Cu3Au(001) shows that ~7 atomic monolayers (MLs) NiMn order antiferromagnetically at room temperature. It is found that NiMn can couple to out-of-plane (OoP) as well as in-plane (IP) magnetized Ni films, the latter stabilized by Co under-layer deposition. The antiferromagnetic (AFM) ordering temperature (TAFM) of NiMn coupled to OoP Ni is found to be much higher (up to 110K difference) than in the IP case, for similar interfacial conditions. This is attributed to a magnetic proximity effect in which the ferromagnetic (FM) layer substantially influences TAFM of the adjacent AFM layer, and can be explained by either (i) a higher interfacial coupling strength and/or (ii) a thermally more stable NiMn spin structure when coupled to Ni magnetized in OoP direction than in IP. An exchange-bias effect could only be observed for the thickest NiMn film studied (35.7 ML); the exchange- bias field is higher in the OoP exchange-coupled system than in the IP one, possibly due to the same reason/s

Temperature-induced sign change of the magnetic interlayer coupling in Ni/Ni25Mn75/Ni trilayers on Cu3Au(001)

We investigated the magnetic interlayer coupling between two ferromagnetic (FM) Ni layers through an antiferromagnetic (AFM) Ni 25Mn75 layer and the influence of this coupling on the exchange bias phenomenon. The interlayer coupling energy of an epitaxial trilayer of 14 atomic monolayers (ML) Ni/45 ML Ni 25Mn75/16 ML Ni on Cu3Au(001) was extracted from minor-loop magnetization measurements using in-situ magneto-optical Kerr effect. The interlayer coupling changes from ferromagnetic to antiferromagnetic when the temperature is increased above 300 K. This sign change is interpreted as the result of the competition between an antiparallel Ruderman-Kittel-Kasuya-Yosida (RKKY)-type interlayer coupling, which dominates at high temperature, and a stronger direct exchange coupling across the AFM layer, which is present only below the Néel temperature of the AFM layer

An overview of fodder resources and animal production in Turkey New approaches for grassland research in a context of climate and socio-economic changes Zaragoza : CIHEAM Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 102 2012 pages 15-

To cite th is article / Pou r citer cet article -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Abstract. In this paper, roughage resources of Turkey were reviewed. Problems and recommendations were discussed for sustainable animal production in the country. Hay production and forage crops acreage have increased significantly last two decades owing to governmental incentives but there is still gap in sufficient quality forage in the country. The forage gap is mainly compensated with cereal straw which is too far to meet animal maintenance need. Some serious measurements such as regulation of grazing season, grazing capacity and selection of proper animal species for rangelands are needed. With respect to forage crops production, solving seed problems and marketing, and determining roughage prices considering feed quality are especially important challenges. Finally producers have to be trained on animal feeding and raising and rangelands management. Keywords. Turkey -Animal raising -Rangeland -Forage production. Une vue d'ensemble des ressources fourragères et de la production animale Turquie Résumé. Dans cet article, les ressources en fourrage de la Turquie ont été examinés. Les problèmes et les recommandations ont été examinées pour la production animale durable dans le pays. Les surfaces de foin et de cultures fourragères ont augmenté de manière significative ces deux dernières décennies en raiso

Thickness Dependent Magnetic Properties of Polycrystalline Nickel Thin Films

Magnetization directions of ferromagnetic ultra-thin films can be altered by increasing the thickness. The transition between in-plane and out-of-plane axes is induced by the competition among the magnetostatic, magnetocrystalline and magnetoelastic anisotropy energies. Such an effect has attracted more interest recently, due to the applications in magneto-optical recording technologies. In this study, we have investigated by magneto-optical Kerr effect the magnetization properties of magnetron sputtered nickel thin films

Investigation on magnetic properties of soft/hard magnetic bilayers at different temperatures: A Monte-Carlo study

Soft/hard magnetic bilayers are attractive systems for investigating their physical behavior due to scientific curiosity and the potential for technological applications. Thus, 10 nm thick hard magnetic layer placed on a 20 nm soft magnetic layer was modeled in this work. After the constructing of magnetic thin films, the bilayer structure was simulated based on micro-magnetic modeling. When constructing the Hamiltonian of the system, magnetocrystalline anisotropy term was also under debate with classical Zeeman and exchange terms. Energy minimization in the simulation was performed using Metropolis algorithm and Markov Chain Monte Carlo (MC-MC) method. As a result of modeling, hysteresis curves, remanent magnetization and coercive fields were obtained at different temperatures

The effects of deposition potential on the optical, morphological and mechanical properties of DLC films produced by electrochemical deposition technique at low voltages

Diamond-like carbon (DLC) films were electrochemically deposited onto indium tin oxide (ITO) substrates using acetic acid and deionized water as electrolyte at low deposition voltages (2.4 V and 60 V). The transmittance of the films was investigated by UV spectrometry. Transmittance measurements versus wavelength revealed that the films transmit 86 % to 89 % light in visible region and band gap of the films varies between 3.87 eV and 3.89 eV. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used for structural characterization to evaluate surface morphology of the DLC films. The grain size and the surface roughness increased for the films prepared at higher deposition potential, while their measured average height decreased. The mechanical properties (hardness H and elastic modulus Er) were determined from load-displacement curves which were obtained by using nanoindentation method. Hardness and elastic modulus of the films increased as the deposition voltage of the films increased from 2.4 V to 60 V. © 2019 Naim Aslan et al., published by Sciendo 2019