Materials Literature
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Self-consistent spin–polarized electronic structure calculations have been carried out to derive the magnetic properties of the Sm2Fe17−xAx (A=Al, Ga, Si and x=0 and 1). The influence of impurities on the Curie temperature (TC) of Sm2Fe17 has been studied using the spin–fluctuation approach of Mohn and Wohlfarth. The…
We have explored the colossal magnetoresistance (CMR) effect in the antiferromagnetic La0.5Ca0.5MnO3 compound. In the absence of a magnetic field (H), the solid is a canted antiferromagnetic (AFM) insulator. An applied H in the Tesla scale induces a first order AFM to FM phase transition, and correspondingly, an insul…
We have applied a multiphonon-assisted energy transfer model, which has been verified for the Yb-doped InP system, to Er-doped GaAs, Nd-doped GaP, and Nd-doped GaAs. By applying this model, the temperature dependence of the decay time of the 4f-shell luminescence can be calculated using two parameters. One parameter i…
In order to understand the magnetic properties of the substituted rare-earth-iron alloys, it is especially important to know the location of the substitutional atoms within the iron lattice. The site distributions of some nontransition-metal substituents in the substituted Nd2Fe17−xTx alloys have previously been repor…
The problem of direct transition intensities in angle-resolved UV photoelectron spectroscopy is addressed. We demonstrate that the angular distribution of intensities integrated over the full $3d$ band of copper is dominated by final-state scattering effects much like those observed in the diffraction of core level ph…
Systematic magnetization and ferromagnetic resonance (FMR) measurements have been performed on thin-film samples of La0.67Ba0.33MnOz (TC∼340 K). It is found from the FMR data that as- grown films show broad lines whose width Γ increases to nearly 1 kOe as T reduced to 77 K. The increase roughly follows the increase in…
Using density-functional methods, we study the electronic structures of the lanthanum-based ‘‘double-exchange’’ perovskite magnets. Antiferromagnetic insulating solutions are obtained for both the end members, LaMnO3 and CaMnO3, within the local density approximation (LDA), with the Jahn-Teller (JT) distortion of the…
This letter addresses the temperature dependence of some of the electrical properties of 0.2-μm-thick SrBi2Ta2O9 capacitors with platinum electrodes on silicon wafers for nonvolatile memory applications. Investigations of the remanent polarization, the nonvolatile polarization and the coercive field with pulse amplitu…
Spring magnets consist of a mixture of exchanged coupled, hard and soft magnetic phases and exhibit improved energy products and remanence. In this study, magnets containing a mixture of Nd2Fe14B and Fe3B have been fabricated using melt spinning under either Ar or He atmospheres. In addition, samples have been heat tr…
Ba-hexaferrite thin films for recording media applications are often fabricated by a two-step process: sputter deposition of an amorphous precursor, followed by annealing to crystallize the BaFe12O19 phase. The magnetic anisotropy of the crystalline films can be either in-plane or perpendicular, depending on the sputt…
Previously, nuclear magnetic resonance experiments and diffusion calculations have indicated that the distribution of nitrogen atoms in a Y2Fe17Nx particle with intermediate N content is characterized by a nitrided region and an unnitrided region. In order to directly detect this two-region configuration, x-ray diffra…
Calculation of the unstrained band offsets between conventional zinc-blende II-VI superlattices (ZnS/ZnSe/ZnTe), or between magnetic II-VI superlattices (MnS/MnSe/MnTe) or combinations thereof ($\frac{\mathrm{Mn}X}{\mathrm{Zn}X}$) show that (i) the range of offsets spanned by different magnetic II-VI superlattices is…
We study the stability range of coherent Ge quantum dots with an epitaxial Si shell. The critical radius is evaluated as a function of Si shell thickness and Ge nanocrystallite radius by comparing the energy of the system in the coherent and incoherent state. We find that the system is coherent up to a Ge nanocrystall…
We report a spin analysis of core-level photoelectrons excited by circularly polarized x rays from a non-magnetic solid. In a combined experimental and theoretical study, we show that the spin-orbit-split W $4{f}_{\frac{7}{2}}$ and $4{f}_{\frac{5}{2}}$ photoemission lines from W(110) exhibit high spin polarizations of…
The magnetic properties of the ferromagnetic compounds, SmFe11Ti and SmFe11TiH1−δ, which are potential candidates for high performance permanent magnets are investigated. At room temperature both compounds exhibit a uniaxial anisotropy, with the easy direction of magnetization parallel to the tetragonal axis. High fie…
For high sensitivity magnetoresistive (MR) transducers, the role of interstrip gap is examined as a design parameter. This is modeled using analytic and numerical approximations. As the gap is narrowed the range of linearity of the MR transducer decreases and the sensitivity increases. For gap/width ratio exceeding 1.…
Coercivity optimization studies were done on melt-spun nanocomposite Nd4R2Fe87−xNbTxB6 (R=Nd,Y,Dy; T=Ag,Cu) isotropic ribbon samples. The maximum attainable coercivities, after adjusting the annealing time, were found to be very sensitive to the annealing temperatures. The optimum magnetic properties [HC=3.9 kOe, (BH)…
The nested carbon nanotubes discovered by Ijima and co-workers as a by-product of fullerene production extended the dimension and geometries of fullerenes into the domain of nanoparticles. These nanotubes are fiberlike structures consisting of concentric graphite sheets nested along the axis extending as long as sever…
The mechanism of magnetostriction in transition metal bulk (fcc Co) and thin films [Co/Pd(001) and Co/Cu(001)] is investigated using the ab initio full potential linearized augmented plane wave method. With the aid of the state tracking and torque approaches the magnetocrystalline anisotropy energy, the essential ingr…
Texture development in 3% Si steel sheets by the manganese removal and decarburization process has been investigated. The 3% Si steel sheets that contain Mn and C were first annealed in vacuum at α-ferrite (α)/austenite (γ) duplex or γ phase temperatures, and then decarburized. During the vacuum annealing a manganese…