Magnetic Properties of the Ce(Pd1−x Cu x )3 System

CePd₃ is an intermediate valence compound with a variety of interesting electronic properties resulting from the partially filled f-shell electrons of cerium atom. Substitution on cerium site with Cu causes a dramatic change in the electronic behavior of the compound. In this work, Ce(Pd_1?x Cu _x )₃ system, 0 ≤ x ≤ 0.133, with x = 0, 0.017, 0.033, and 0.133, has been synthesized by arc melting method. The powder X-ray diffraction reveals that the compounds crystallize in AuCu₃-type structure where copper enters the lattice substitutionally. Magnetic susceptibility measurements as a function of temperature have been carried out on these alloys which show that with increasing copper content x, the alloys Ce(Pd_1?x Cu _x )₃ show a smooth crossover from the weak temperature dependence of CePd₃ to a Curie-Weiss behavior for higher concentrations of x. The value of μ _eff increases with x, while the paramagnetic Curie temperature shows a large reduction with increase in x; this suggests a very rapid decrease in the Kondo temperature with x.     

Co–C and Pd–C Eutectic Fixed Points for Radiation Thermometry and Thermocouple Thermometry

Two Co–C and Pd–C eutectic fixed point cells for both radiation thermometry and thermocouple thermometry were constructed at NMC. This paper describes details of the cell design, materials used, and fabrication of the cells. The melting curves of the Co–C and Pd–C cells were measured with a reference radiation thermometer realized in both a single-zone furnace and a three-zone furnace in order to investigate furnace effect. The transition temperatures in terms of ITS-90 were determined to be \(1324.18\,{^{\circ }}\hbox {C}\) and \(1491.61\,{^{\circ }}\hbox {C}\) with the corresponding combined standard uncertainty of \(0.44\,{^{\circ }}\hbox {C}\) and \(0.31\,{^{\circ }}\hbox {C}\) for Co–C and Pd–C, respectively, taking into account of the differences of two different types of furnaces used. The determined ITS-90 temperatures are also compared with that of INRIM cells obtained using the same reference radiation thermometer and the same furnaces with the same settings during a previous bilateral comparison exercise (Battuello et al. in Int J Thermophys 35:535–546, 2014). The agreements are within \(k=1\) uncertainty for Co–C cell and \(k = 2\) uncertainty for Pd–C cell. Shapes of the plateaus of NMC cells and INRIM cells are compared too and furnace effects are analyzed as well. The melting curves of the Co–C and Pd–C cells realized in the single-zone furnace are also measured by a Pt/Pd thermocouple, and the preliminary results are presented as well.     

Superconducting Properties in Amorphous MgxB1−x Films

We report the observation of superconductivity in a thick amorphous (a-) Mg_xB_1–x film with x0.3, which was prepared by coevaporation of Mg and B. The resistivity in the normal state is by approximately two order of magnitude higher than that for clean MgB₂ crystals. The transition temperature T _c at which the resistivity vanishes is found to be 6 K, that is even lower than T _c=39 K for clean MgB₂ crystals. The upper critical field extrapolated to zero temperature is about 5 T. Based on the data of resistivity measured down to 0.4 K for various fields B, we construct the possible B–T phase diagram over the broad temperature/field region.     

Magnetic and Microstructure Properties of Ni-Doped ZnO Films and Powder by Sol–Gel Process

Zn_1?x Ni _x O precursor solutions with a different ratio (x=0.01?C0.03) were prepared by sol?Cgel synthesis using Zn and Ni based alkoxide. Reel-to-reel sol-dip coating method was used to grow Zn_1?x Ni _x O films. Zn_1?x Ni _x O powders and films, annealed at various temperatures, were tried to observe the doping ratio and temperature effects on magnetic and microstructure properties. The surface morphologies of all samples were characterized by ESEM and EDS. The crystal structures of the ZnNiO powders were characterized using 2???C?? x-ray diffraction (XRD). The alterations of the lattice parameters have been obtained by the TREOR program. ESR spectra of Zn_1?x Ni _x O powder samples were collected at room temperature. The magnetization and microstructure of the powders and films with different dopant ratios, temperature, and the time of annealing process are presented.     

The Magnetic Properties of Mn x Fe1−x NiSi (x=0,0.25,0.5,0.75,1) Alloys

The magnetic properties of Mn _x Fe_1?x NiSi (x=0,0.25,0.5,0.75,1) alloys are studied using density functional theory and the WIEN2k package. The exchange correlation potential is treated by generalized gradient approximation (GGA). The total energy calculations of these alloys confirm the stability of the ferromagnetic phase as compared to a nonmagnetic phase. The total magnetic moment is not a linear function of x. By increasing x, it increases and then decreases. The peak position of the magnetic moment is near x=0.75.     

Investigation of Structural, Magnetic and Magnetotransport Properties of Electrodeposited Co–TiO2 Nanocomposite Films

Nanocomposite Co?CTiO₂ thin films were prepared by simultaneous electrodeposition of Co and TiO₂ on a Cu substrate from a solution based on Co sulfate in which TiO₂ nanoparticles were suspended by stirring. We investigated the influence of the TiO₂ nanoparticles concentration in the bath on the morphology, composition, magnetic and magnetotransport properties of the films. The Co?CTiO₂ thin films were characterized by using scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction analyses, and their magnetic properties were evaluated by using an induction type device with data acquisition system and a torque magnetometer. The current in-plane transport properties of the films have been investigated. The results showed that the films were composed of a Co metal matrix containing embedded TiO₂ nanoparticles and cobalt hydroxide which is formed simultaneously with cobalt metal deposition. The amount of TiO₂ in the film increases with the rising concentration of TiO₂ nanoparticles in the plating bath. This complex structure favored the increase of the magnetoresistance. The Co?CTiO₂ nanocomposite films (containing about 1.3 at.% Ti) exhibit a giant magnetoresistance contribution of 47.6 %. From the magnetic measurements, we have found that the saturation magnetization, the magnetic susceptibility, and the effective magnetic anisotropy constant decrease with the increasing content of TiO₂ in the thin layer. The easy magnetization axis direction changes from in-plane to almost perpendicular-to-plane, with increasing TiO₂ nanoparticles content in the film. The existence of a giant magnetoresistance effect in Co?CTiO₂ is very promising for potential applications in spintronics.     

Magnetic Anisotropy and Magneto-Transport Properties of Co–Ni–N Granular Alloys Thin Films

The effect of nitrogen addition on the morphology, magnetic anisotropy, and magnetoresistance properties of Co–Ni–N granular thin films were investigated. The films were grown by electrodeposition onto aluminum substrates at room temperature. By a complex process of cationic catalysis occurring at the cathode/electrolyte interface, nitrogen is adsorbed in the Co–Ni film. Finally, a granular film grows by a tridimensional progressive nucleation mechanism. The nature of the grains and of the interface between them influences exchange interactions between grains, which play an important role in determining the magnetic anisotropy. From the magnetic measurements, we found that the magnetic anisotropy constant varied in the range K _eff=(−21.5÷36.6)×10⁴ J⋅m⁻³ and the coercivity varied between H _c=(13÷67) kA⋅m⁻¹ depending on the sodium nitrate content in the plating bath. The Co–Ni–N granular thin films display large values (∼160%) of magnetoresistance. These large values of magnetoresistance make such structures attractive for applications as sensitive magnetic field sensors.     

Electrical and Optical Properties of GaSe Thin Films

The structure, electrical transport, and optical properties of GaSe films fabricated by means of radio-frequency (RF) magnetron sputtering in Ar were investigated. The as-sputtered GaSe films were amorphous, and their optical energy gap Eg are 1.9～2.6 eV. The effect of the synthesis conditions on the optical and electrical properties of the GaSe films has also been studied     

Study on the Structure,Vacancy Defect,and Magnetic Properties for Gd1−xCexMnO3 Ceramics

Journal of Superconductivity and Novel Magnetism - The effects of the Ce doping on the structure, vacancy defect, and magnetic properties of the Gd1?xCexMnO3 polycrystalline samples...     

Magnetic Properties of Nanometer-Scale NiZnCu Ferrite Thin Films Fabricated by Spray-Spin-Heating-Coating Method

A new nanometer-scale ferrite thin film with excellent high-frequency characteristics has been developed by the spray-spin-heating-coating method. The effects of the ion synthesis mechanism, chemical stoichiometry, fabrication method, and doping content on the magnetic properties and microstructure of the thin films have been analyzed. The films formed between 75℃ and 90℃ by spray-spin-heating-coating methods was discovered with fine grain size of about 21 nm, high saturation magnetization (4πMs) of about 6.5 kGs, coercivity of about 9.8 Oe, as well as initial permeability of about 14.0. These films can be widely used in radio-frequency integrated circuit devices.     

Magnetic Field Effects on Surface Morphology and Magnetic Properties of Co–Ni–N Thin Films Prepared by Electrodeposition

The surface morphology and magnetic properties of Co?CNi?CN thin films electrodeposited under an external magnetic field were investigated. The films were electroplated on Al substrates using the same electrodeposition parameters (temperature and pH) for all experiments, with an external magnetic field of 107?Oe applied to the cathode surface. The films were compared with similar samples obtained in the absences of magnetic field. The magneto-induced modifications in the Co?CNi?CN morphology can be explained by the specific local convection of ions at the interface cathode-electrolyte, which promotes changes both in the electrical charge of the double layer and in the thickness of the diffusion layer. From the magnetic measurements, we found that the coercivity varied between H _c =(14÷27)?kA/m depending on the direction of the applied magnetic field and on the sodium nitrate content in the plating bath. It was observed that an induced anisotropy appeared in the Co?CNi?CN films due to the preferential orientation of the easy axis of magnetization in the magnetic field direction. In addition, the Co?CNi?CN alloy films showed good magnetic property, which is considered that not only the smaller grain size of the films, but also more uniform surface of the films than that deposited in absence of applied magnetic field.     

Effect of Ni Doping on Structural,Morphological, Optical and Magnetic Properties of Zn1−x Ni x O Dilute Magnetic Semiconductors

Ni²⁺-doped ZnO diluted magnetic semiconducting materials (Zn_1?x Ni _x O with x=0.01,0.02,0.03,0.04,0.05) were synthesised by the co-precipitation method. All synthesised samples were sintered at 600 °C for 6 hours. The effects of Ni²⁺ ion-doping on the structural, morphological, optical and magnetic properties of ZnO were investigated using powder X-ray diffraction, field emission SEM, UV–DRS spectroscopy, photoluminescence and vibrating sample magnetometry. The XRD patterns of pure and Ni-doped ZnO samples revealed single phase hexagonal wurtzite structure. The SEM analysis revealed the morphology of prepared samples, and the chemical compositions of all samples were analysed using exhibit energy density X-ray analysis (EDAX) characterisation. The absorption and emission properties revealed the effect of Ni²⁺ doping in ZnO samples. All Ni²⁺ ion-doped samples showed ferromagnetism at room temperature. The observed results are here analysed and reported.