Materials Literature
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Superlattice structures based on doped Mn-oxides and SrTiO3 exhibit desirable magnetotransport properties, such as an enhanced magnetoresistance (MR) and a broadened MR transition. An La0.7Ca0.3MnO3 (55 Å)/SrTiO3 (160 Å) superlattice shows 61% MR at 0.5 T and 109 K, defined by [R(0 T)−R(0.5 T)]/R(0 T), compared to 38%…
We have studied magnetic and magnetotransport properties of novel III-V diluted magnetic semiconductors, (Ga1−xMnx)As. The GaMnAs thin films were grown on GaAs(001) substrates by low temperature molecular beam epitaxy. We present magnetoresistance, extraordinary Hall effect, and M–H characteristics of two (Ga1−xMnx)As…
We present the results of direct measurements of the isothermal compressibility up to 13 kbar on Nd2Fe17 and Nd2(FeTi)17 compounds and the results of measurements of the linear thermal expansion on Nd2Fe17 compound under hydrostatic pressure up to 6 kbar in temperature range 200–400 K covering both ferromagnetic and p…
The influence of a substitution of Mn for Fe in the Sm2(Fe,Mn)17Nx alloys on the structure and the magnetic properties was studied. Sm2(Fe,Mn)17Nx alloy powders of 32–74 μm in particle size with several values of x were successively synthesized using NH3+H2 gas. It was found that the primary phase of the powders maint…
The transition-metal oxide ${\mathrm{La}}_{2}$${\mathrm{NiO}}_{4}$ is studied using a multiband Hubbard model with a Hund coupling J. We obtain its mean-field phase diagram in the U- (correlation strength on Ni sites) \ensuremath{\Delta} (charge-transfer energy) plane. For J=0 we have a continuous transition from a pa…
Isopiestic measurements of solvent uptake have been made in the synthetic isoprene/benzene system for both crosslinked and uncrosslinked polymers in order to revisit the question of the swelling activity parameter S. Both the nonzero value of S at zero swelling and the appearance of a peak in S vs. degree of swelling…
To get a deeper insight into the mechanism involved in the flux reversal of Co based wire we have tickled the wire with an ac field of smaller amplitude than the switching field, H*, and observed the signal induced in a pancake coil moved along the wire, vibrated a small coil along the wire and observed the induced si…
A local model based on the idea of atoms distributed within a crystalline lattice and following a binomial probability method for describing the hyperfine field distributions obtained from the room temperature Mössbauer spectra of the disordered Fe–Ni system is presented. This model allows one to calculate the mean hy…
The calculated transmission of microwave power at GHz frequencies through Terfenol-D (Tb0.27Dy0.73Fe2) is strongly influenced by the enormous magnetostriction parameter of this material. For conditions satisfying ferromagnetic resonance there is a peak in the transmission corresponding to sound and spin waves transpor…
The dielectric constant of a monolayer with dielectric anisotropy on a material surface was calculated with consideration of the local field acting on polar molecules. In the calculation, a monolayer of constituent rodlike molecules with a permanent dipole moment not parallel to the molecular long axis is assumed to f…
A low concentration of substitutional impurities such as Ga or Si in R2Fe17 (R=rare earth) raises its Curie temperature. Self-consistent spin-polarized electronic-structure calculations are performed and exchange parameters (Jij) are derived from first-principles for pure Sm2Fe17 and Sm2Fe16A (A=Ga, Si). The changes i…
In Nd2Fe17−δCrδ (δ=0, 0.5, 1, 1.9), Cr substitutes for Fe atoms without changing the crystal structure. Neutron diffraction measurements show that for all values of δ, Cr preferentially substitutes for Fe in the 6 c site and randomly substitutes for Fe in the 18 f site. Cr substitution can be explained by considering…
A series of amorphous and partially crystalline giant magnetostrictive thin films of the composition (Tb0.3Dy0.7)39Fe61 has been prepared by dc magnetron sputtering. The sputtering conditions were the same for all samples apart from the substrate temperature TS, which varied between 330 and 510 °C. The crystalline sta…
Local-density approximation ab initio band-structure calculations have been carried out on the misfit compound (LaS)(SrS${)}_{0.2}$${\mathrm{CrS}}_{2}$. It appears that this phase can be regarded as an infinite two-dimensional intercalation compound. One electron is transferred from the LaS slab to the ${\mathrm{CrS}}…
Spin reorientation of Nd2Fe14B with different degree of grain sizes was detected by measuring the temperature dependence of the ac susceptibility. The studied materials include: (1) a spherical Nd2Fe14B single crystal that shows no coercivity. (2) Microcrystalline Nd2Fe14B obtained by induction-melting or by sintering…
Iron losses can account for a significant portion of the total loss in electrical machines. Nevertheless, although analytical and numerical techniques have been developed for predicting the iron loss density distribution and the total iron loss of various types of machine under any operating load condition, to date th…
A theory is presented to calculate the electron inelastic scattering cross section for a moving electron near the surface region at an arbitrary takeoff angle. The theory is based on using a bulk plasmon-pole approximation to derive the numerically computable expression of the electron self-energy in the random-phase…
At cryogenic temperatures magnetic properties of ferrites change significantly from their values at room temperature, which has been the main regime for most device applications. Recently, microwave ferrite devices with superconducting microstrip circuits have been demonstrated at a temperature of 77 K with virtually…
We have investigated how plastic deformation changes the yield stress and the magnetic properties of an ultralow carbon sheet steel. Plastic strains up to 10% nearly doubled the yield stress from 150 to 290 MPa (22–42 ksi), and the coercive field from 0.17 to 0.31 kA/m (2.1–3.9 Oe). The effects on other magnetic prope…
The sorption and transport of four aliphatic hydrocarbons into natural rubber crosslinked by different vulcanization systems [conventional (CV), efficient (EV), peroxide (DCP) and a mixed system consisting of sulfur and peroxide (mixed)] were investigated in the temperature interval of 28–60°C. Of the four systems, na…