Materials Literature
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A general sum rule has been established recently, bounding the integral of the gyromagnetic losses weighted by the frequency, by the square of the saturation magnetization [O. Acher and A. L. Adenot, Phys. Rev. B 62, 11324 (2000)]. This rule has been established for soft materials with internal anisotropy fields small…
We have prepared homogeneous SmCox (x=5–26) sputtered thin films of thickness 500 nm with excess Co compared to SmCo5. The purpose is to determine how any spring exchange incorporated by the excess Co improves the energy product. Films are subjected to a 30 s or 20 min anneal to crystallize the Sm–Co. In the case of b…
Abstract Poly(methyl methacrylate) (PMMA) was γ‐irradiated (5–20 kGy) by a 137 Cs source at room temperature in air. The changes in the molecular structure attributed to γ‐irradiation were studied by mechanical testing (flexure and hardness), size‐exclusion chromatography, differential scanning calorimetry, thermal gr…
The photoluminescence properties of ZnO/ZnMgO multiquantum wells have been investigated by continuous and time-resolved photoluminescence spectra at various temperatures. Strong first-order and second-order longitudinal optical (LO)-phonon replicas were observed in the emission spectra. Both the zero-phonon emission a…
Soft, high moment materials are crucial for the magnetic data recording industry in applications such as write poles and soft underlayers. Ever increasing areal densities have pushed the requirements for materials exhibiting saturation magnetizations above 2 T. In this work we investigate nanocrystalline FeCoB which e…
Six selenium variants of BEDT-TTF have been successfully synthesized by a newly developed synthetic method that involves a combination of two key reactions for the construction of two kinds of heterocyclic rings: the first is a one-pot formation of 1,3-dichalcogenole-2-chalcogenones from a common starting material, TH…
Polycrystalline Ni–Mn–Ga thin films have been deposited by the pulsed laser deposition (PLD) technique, using slices of a Ni–Mn–Ga single crystal as targets and onto Si (100) substrates at temperatures ranging from 673 K up to 973 K. Off-stoichiometry thin films were deposited at a base pressure of 1×10−6 Torr or in a…
Electron energy-loss (EEL) spectroscopy performed near dislocation cores is one of the few experimental techniques that can yield valuable information about the electronic levels associated with dislocations. In this study, we present experimental observations of low-loss EEL spectroscopy acquired on grain boundary di…
Pb 1−x Ca x TiO 3 (0.10⩽x⩽0.40) thin films on Pt/Ti/SiO2/Si(100) substrates were prepared by the soft solution process and their characteristics were investigated as a function of the calcium content (x). The structural modifications in the films were studied using x-ray diffraction and micro-Raman scattering techniqu…
Ni–Zn ferrite films were prepared by spin-spray ferrite plating method at 90 °C on glass substrates from a reaction solution of FeCl2(+FeCl3)+NiCl2+ZnCl2 and an oxidizing solution of NaNO2+CH3COONH4. The complex permeability μ=μ′−iμ″ values of the as-plated films were measured at frequencies up to 3 GHz. The Ni0.28Zn0…
We derive a rigorous f-sum rule for the spin conductivity D(ω), valid in the paramagnetic regime of any itinerant system with nearest-neighbor hopping, assuming only that the potential energy conserves the total spin at each site. Two such itinerant systems are the double-exchange and Hubbard models. According to the…
The effects of the eight kinds of additives, such as Al, BN, C, MoS2, Si, Zn, oleic acid, and diethylene glycol on the magnetic properties of the single stage hot deformed NdFeB magnets had been investigated in this work. Among these additives, it was observed that MoS2 and Al were more effective in increasing remanen…
The compound (CH3NH3)2MnCl4 had for a long time been considered a good example of a quasi-two-dimensional Heisenberg antiferromagnet, however, it is a weak ferromagnet with a nearly quadratic layer structure. In this work we measure the magnetization of (CH3NH3)2MnCl4 and the diluted with cadmium compound (CH3NH3)2Mn0…
Magnetic and neutron diffraction studies have been carried out on PrMnSb2. Magnetization data in the temperature range of 5–400 K show two magnetic transitions: one at ∼175 K attributed to the antiferromagnetic ordering of the Mn moments, and the other at ∼35 K possibly due to the antiferromagnetic ordering of the Pr…
The Preisach model is appropriately modified to describe the clockwise hysteresis with the positive saturation state achieved for some positive input value. It is demonstrated that this type of clockwise hysteresis may naturally appear in front propagation problems such as nonlinear diffusion of electromagnetic fields.
Phase evolution and magnetic properties of melt-spun Nd8Fe86B6−xCx (x=0, 2, 4, 5, 6) alloy ribbons have been investigated. Increasing the C content was found to decrease the glass-forming tendency of as-spun ribbons. For samples with low C content (x⩽4), the best magnetic properties were achieved by directly quenching…
Thermal expansion and magnetic properties of the YFe11−xCoxTi compounds have been investigated by various experimental methods. A large magnetovolume effect has been clearly observed below TC for the Fe-rich compounds. When the transition metal concentration changes from Fe to Co rich, the invar-like effect becomes le…
We report an enhanced negative magnetoresistance ratio of about 16% at 4.2 K at 1 T for CrO2/TiO2 composites, compared to CrO2 powder compacts and CrO2/RuO2 composite. The magnetoresistance ratio of 60% at 4.2 K is noted when TiO2 acts as tunneling barrier. The absence of substantial barrier heights with RuO2 grains d…
The effect of the atomic disorder–order transformation on remanence enhancement and coercivity in isotropic CoPt magnets has been studied by isothermal annealing at 675 °C, well below the transformation temperature, for 10–80 min after quenching from 900 °C. The results of x-ray diffraction, alternating-current suscep…
Ultrafine Co1−xZnxFe2O4 (0⩽x⩽1.0) particles are fabricated by a sol-gel method. The magnetic and structural properties of powders were investigated with x-ray diffraction, vibrating samples magnetometer and Mössbauer spectroscopy. The lattice parameter (a0) increases linearly with increasing Zn concentration (x) and f…