Materials Literature
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The $^{2}$E(D)\ensuremath{\rightarrow} $^{2}$${\mathit{T}}_{2}$(D) emission of substitutional ${\mathrm{Cu}}^{2+}$ in ZnO has been observed in the 3700--5800-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ spectral range under 50-keV electron-beam excitation at cryogenic temperatures. The excitation mechanisms of this cath…
A photoemission investigation of Fe-Pd and Fe-Pt transition-metal alloys, using \ensuremath{\sim}50--150-eV synchrotron radiation, is presented. We consider in particular the spectral distribution of Fe states when approaching the dilute limit. By means of the Cooper minimum in the 4d and 5d photoionization cross sect…
Amorphous thin films of (1−x)BiFeO3-xPbZrO3 for x=0.1–0.9 have been prepared by the technique of rf sputtering and the effects of sputtering conditions and annealing at high temperatures on magnetic properties of such films have been studied through magnetization measurements. A sintered polycrystalline target was use…
The properties of NiFeX ternary films (X being Al, Au, Nb, Pd, Pt, Si, and Zr) have been studied for soft-film biasing of the magnetoresistive (MR) trilayer sensor. In general, the addition of the element X into the NiFe alloy film decreases the saturation magnetization Bs and magnetoresistance coefficient of the film…
The angular dependence of the coercive field Hc(ϑ) is discussed as a means of studying magnetization reversal in permanent magnets. We consider Hc(ϑ) for permanent magnets RFeB (R=Pr, Nd) for temperatures between 4.2 and 300 K. At high temperatures, it is found that Hc may increase by a factor 1.5–2 as ϑ increases fro…
Magnetic susceptibility studies of several A2CuBr4 salts, where A is an organoammonium cation, are reported. These salts contain tetrahedrally distorted CuBr2−4 anions. Magnetic exchange pathways exist through interanionic Br⋅⋅⋅Br pathways. In this manner, various types of new antiferromagnetic spin 1/2 magnetic syste…
The electronic structure of PtMnSb has been studied by means of the linear muffin-tin-orbital method of band-structure calculation. In agreement with earlier investigations a so-called half-metallic behavior has been found. Until now, this exotic feature of the band structure of PtMnSb, which is made responsible by so…
The crystal structure of fructose-1,6-bisphosphatase (EC 3.1.3.11) complexed with the product fructose 6-phosphate (F6P) has been refined at 2.1-A resolution to an R factor of 0.177 with root-mean-square deviations of 0.014 A and 2.9 degrees from the ideal geometries of bond lengths and bond angles, respectively. The…
We have examined incident-beam effects in electron-stimulated Auger-electron diffraction (AED) on a cleaved GaAs(110) surface. The results indicate that incident-beam diffraction is significant in an AED experiment, and that the dissipative nature of the incident beam in contributing to the Auger process must be accou…
In situ crystallized barium hexaferrite films have been deposited with a target-facing sputtering system under previously optimized conditions on four different substrates which are: SiO2, ZnO, Gd3Ga5O12, and Al2O3. By using several structural and magnetic characterizations different growth mechanisms were put forward…
We have imaged ten different superstructures on highly oriented pyrolytic graphite near adsorbed platinum particles using a scanning tunneling microscope. These superstructures are localized in small areas near the platinum particles and decay within a distance of 2--5 nm into the graphite lattice. When Fourier transf…
Thin Si films on thermally grown ${\mathrm{SiO}}_{2}$ layers were completely melted by pulsed-laser irradiation. The molten films cool very rapidly (>${10}^{9}$ K/s) until bulk nucleation initiates solidification. The quench rate was varied by changing the thickness of the Si or the ${\mathrm{SiO}}_{2}$ layers. For…
The two-photon absorption (TPA) spectrum of interacting \ensuremath{\pi} electrons in conjugated polymers is shown to be qualitatively different from any single-particle description, including the Hartree-Fock limit. Alternating transfer integrals t(1\ifmmode\pm\else\textpm\fi{}\ensuremath{\delta}) along the backbone…
The Brown paradox1 concerns an order of magnitude discrepancy between micromagnetic theory and experiments: the theoretical nucleation field for an elongated iron specimen is −500 Oe whereas the measured value for high-quality iron whiskers is about 0.1 Oe. It is a fairly widespread view that the paradox may be resolv…
A generalization of the vector Preisach hysteresis model is proposed. This new vector hysteresis model represents a larger class of hysteresis nonlinearities than either the Stoner-Wohlfarth model or the previously developed vector Preisach model. To demonstrate this fact, it will be shown that the Stoner-Wohlfarth mo…
PNb 9 O 25 cristallise dans I4/m avec a=15,639, c=3,8317 A, Z=2; affinement jusqu'a R=0,031. Le reseau est compose de colonnes 3×3×∞ du type ReO 3 . Chaque colonne possede des sommets communs avec les quatre colonnes voisines et des cotes communs avec les tetraedres PO 4
The temperature dependence of the magnetic susceptibility for 1.5<T<300 K, the field dependence of the magnetization M(H), for 0<H<23 T and 1.5<T<15 K, and the temperature dependence of the heat capacity C(T), for 5<T<95 K are reported for the insulating distorte…
A new form for the classical Preisach model of hysteresis which gives the decomposition of this model into reversible and irreversible components is derived. This form reveals that the classical Preisach model does describe (to a certain extent) reversible properties of hysteresis nonlinearities. It is also shown that…
We have explored the impact of low-level Cu additions on the magnetic properties of melt-spun Nd-Fe-B ribbons. The addition of 0.5 at. % Cu enhances the intrinsic coercivity as much as 30% over that of Cu-free materials. Transmission electron microscopy analyses demonstrate that Cu segregates preferentially to the int…
In general, the stoichiometry of melt-spun ribbons and subsequent hot-worked Nd-Fe-B magnets derives from the composition of the starting ingot. We have shown, however, that it is possible to introduce small amounts of powdered metals into the ribbons after the ingot has been melt spun. Many elements, when mixed with…