bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kondo‐Type Resistivity Anomaly in Noble Metal Alloys with 3d Metals
Authors: Inoue K. , Nakamura Y. 
Published: July 2007

AbstractThe electrical resistivities of the f.c.c. Au‐V, Au‐Mn, Au‐Fe, and Au‐Ni alloys with high concentration of 3d‐element impurities have been measured from 4 to 1000 K. The results were analyzed together with other data for Au‐Cr, Au‐Co, Ag‐Mn, Cu‐Mn, and Cu‐Ni alloys. At high temperatures, the decrease of magnetic resistivity with increasing temperature is observed for Au‐V, Au‐Cr, Au‐Mn, Au‐Fe, Au‐Co, Ag‐Mn, and Cu‐Mn alloys and is expressed empirically by the equation Rmag(T) = ‐ c (Y + Z c) ln (T2 + + X2 c2)1/2 + c (R1 + R2 c), except for Au‐Co alloys, where c is the concentration of 3d element, T the temperature, and X, Y, Z, R1, and R2 are constants. Yc coincides with the coefficient of ln T in each dilute alloy. R1, c coincides with the temperature independent term in each dilute alloy. Xc is nearly of the same order as the RKKY interaction strength. Au‐Ni and Cu‐Ni alloys do not show such a decrease. The maximum of magnetic resistivity observed for Au‐Cr, Au‐Mn, Au‐Fe, Ag‐Mn, and Cu‐Mn alloys is explained by the destruction of very short range ordering, such as pairs and triplets, remaining far above the Néel temperature.
Electronic Energy Loss of Ions in the Modified Firsov Theory
Authors: Komarov F. F. , Kumakhov M. A. 
Published: July 2007

AbstractAn analytical version is derived of the modified Firsov theory for the calculation of inelastic energy losses of ions traversing through crystalline and amorphous targets. Shell effects are included. The model describes correctly the dependence of the inelastic energy loss on the atomic number of the target atoms and incident ions and yields a fair agreement with experimental data.
Long‐Range Forces in the Dynamics of Crystals with Defect
Authors: Litzman O. , Rózsa P. 
Published: July 2007

AbstractA point defect with long‐range interaction changes the dynamical matrix of the ideal crystal in infinitely many elements. The method for the evaluation of the local modes and of the Green's function of this problem proposed earlier is extended in order to apply it to the case when interstitials are present. The use of some more general formulae enables the final formulae to be stated in a surprisingly clear form.
High Field Transport in n‐InSb at 77 °K and the Solution of Boltzmann's Equation by Iteration
Authors: Stokoe T. Y. , Cornwell J. F. 
Published: July 2007

AbstractThe solution of Boltzmann's equation for n‐InSb at high fields and 77 °K is obtained by Rees' iterative method. The time independent solution obtained is in agreement with a recent Monte‐Carlo calculation by Fawcett and Ruch and experimental results by Neukerman and Kino. A comparison between the Boltzmann solution and the drifted Maxwellian approach previously discussed by the authors is also presented.
Dynamical Properties of the Singlet—Singlet Van Vleck Paramagnet
Authors: Cheung T. H. 
Published: July 2007

AbstractThe high temperature dynamical properties of the singlet—singlet model for the Van Vleck paramagnet is investigated. Such a system can be described by the Hamiltonian of the Ising model with a transverse field. Using the high temperature approximation of Mori's continued‐fraction representation, an approximate expression for the longitudinal relaxation function is derived. This leads to renormalized magnetic excitations and the appearance of a central peak for the corresponding spectral density. Its relevance to recent neutron scattering data is discussed.
Stress and Magneto‐Optical Studies of F‐Centres in SrCl2
Authors: Billardon M. , Duran J. , Lefrant S. , Taurel L. 
Published: July 2007

AbstractMagneto‐optical and stress linear dichroism studies are made on the new F centre found in SrCl2 which belongs to Td symmetry group. The results have been analysed by the method of moments in order to determine a number of useful parameters. It is found that the excited state orbital Landé factor is close to zero. This is explained by taking into account an admixture of |p〉 and |d〉 type orbitals in the excited state. It is found that the spin—orbit splitting is about — 100 cm−1. A careful analysis of higher order moments of the magnetic circular dichroism and stress linear dichroism curves leads to a determination of the dynamic electron lattice coupling parameters which can in turn be compared to the static parameters determined from the first order moment of the stress linear dichroism curves. The dynamic electron lattice interaction is predominantly due to a trigonal vibrational mode whose mean frequency is about 100 cm−1.
Magnetic Properties of Manganese‐Doped Mercury Telluride
Authors: Savage H. , Rhyne J. J. , Holm R. , Cullen J. R. , Carroll C. E. , Wohlfarth E. P. 
Published: July 2007

AbstractThe inverse susceptibility—temperature curves of MnxHg1—xTe (x = 0.05, 0.11, 0.17, 0.235) showed a Curie‐Weiss behaviour at high temperatures and a downward deviation at low temperatures. The paramagnetic Curie temperatures and effective numbers of magnetic carriers also deviated from a linear dependence on x at low values of x. These results were explained in terms of a cluster model at low x values and a molecular field model at high x.
The Energy Bands and the Fermi Surface of β′AgZn
Authors: Skriver H. L. 
Published: July 2007

AbstractThe electronic energy band structure for the ordered alloy β′AgZn has been calculated by the augmented plane wave method. The bands obtained are similar to those of β′CuZn except for the d‐band parameters: width and position. Various density‐of‐states functions have been determined. The calculated ϵ2(ω) profile is in agreement with static reflectance measurements. A Fermi surface model has been derived. The angular dependence of various extremal cross sections agrees extremely well with existing de Haas‐van Alphen experiments. Cyclotron masses have been estimated and compared to the experimental values giving the apparent mass enhancement.
Nonlinear Heat Transfer in a Lattice Containing Impurities
Authors: Dubey K. S. 
Published: July 2007

AbstractNonlinear heat transfer in a lattice has been studied considering two scattering mechanisms, isotopic scattering and dislocation scattering as impurity scattering process. A sufficiently good agreement is observed between the experimental conductivity of NaF in the entire temperature range 2 to 10 °K.
On the Mechanism of Small‐Polaron Transport
Authors: Klinger M. I. 
Published: July 2007

AbstractA model of the mechanism of (nonadiabatic) small polaron transport is considered for intermediate temperatures when the coherence of the Bloch band states is significantly destroyed but thermally activated hops still do not dominate. The mechanism of small polaron tunneling is studied at high temperatures when the scattering is fairly strong (quantum diffusive motion).
Considérations sur l'importance de quelques hypothèses physiques dans la théorie de l'émission électronique secondaire
Authors: Moulin B. , Ganachaud J.‐P. , Cailler M. 
Published: July 2007

AbstractOn propose un certain nombre de corrections à apporter au travail théorique d'Amelio ainsi qu'une nouvelle méthode de résolution plus rapide et moins contraignante. On considère ensuite l'influence de l'hypothèse restrictive de la constance du libre parcours moyen des électrons sur la distribution énergétique de l'émission électronique secondaire. On considère aussi l'influence de la fonction source.
Contributions to the hyperfine field at the 57Fe nucleus in crystals with garnet structure
Authors: Valentin R. 
Published: July 2007

AbstractENDOR measurements are performed on a number of Fe3+ doped crystals with garnet structure (YAIG, LuAlG, TmAlG, YGaG, LuGaG, TmGaG, and EuGaG) which enabled to determine the hyperfine field at the 57Fe nucleus. The Fe3+ ions occupy cation sites ((a)‐sites) which are surrounded by oxygen octahedra. It is found that the hyperfine field is linear dependent on the trigonal part of the crystal field at the (a)‐site, and thus on the field gradient Vzz. This dependence is attributed to the dipole‐dipole interaction between electron and nuclear spins which in higher order contributes to the hyperfine field.
A KKR approach to electronic spectra of amorphous semiconductors
Authors: Maschke K. , Overhof H. , Thomas P. 
Published: July 2007

AbstractA new method is proposed to calculate the configurational averaged Green's function for amorphous semiconductors. In contrast to earlier work based on pseudopotentials this method is within the framework of the KKR approach. It, therefore, can avoid the approximations for the potential average necessary in the pseudopotential scheme. Some general properties of the resulting spectral function and density of states are discussed.
The influence of the short‐range order on the energy spectrum of disordered tellurium phases
Authors: Kramer B. , Maschke K. , Laude L. D. 
Published: July 2007

AbstractThe influence of different types of short range order on the density of states of tellurium is investigated. The results for usual trigonal short range order are compared to those for simple cubic short range order. The density of states for the corresponding systems without long range order is discussed within the framework of the complex band structure method. The results are compared to photoemission experiments for different modifications of disordered tellurium.
Theory of scattering yield in channeling
Authors: Ohtsuki Y. H. 
Published: July 2007

AbstractMaking use of the non‐local potential due to inelastic scattering, an expression for the transition probability of inelastic scattering in Channeling is introduced. The theory of back‐scattering yield oscillation is studied as a demonstration. Expressions for the blocking pattern and the star pattern are also presented in terms of the transition probability in channeling.
Mössbauer spectrum depending on the degree of spin‐system ordering
Authors: Selyutin G. Ya. 
Published: July 2007

AbstractA theoretical investigation is made of the Mössbauer spectrum in crystals containing exchange coupled magnetic ions. It is shown that for a Lorentz shape of the Mössbauer line the line broadening, the Debye‐Waller factor describing the intensity of the Mössbauer spectrum, and the line shift depend on the value of exchange interaction of magnetic ions and on the degree of spin‐system ordering.
The hyperfine fields in ferromagnetically ordered cubic Laves phase compounds of gadolinium with non‐magnetic metals
Authors: Dormann E. , Buschow K. H. J. 
Published: July 2007

AbstractBy means of current zero‐field spin‐echo NMR technique the hyperfine fields at the Gd and X sites in the ferromagnetic cubic Laves phase compounds of the type GdX2 (X = Al, Pt, Ir, Rh) are derived. The easy direction of magnetization in GdIr2 is [100] in contrast to [111] in GdAl2.
On the theory of phonon‐like excitations in noncrystalline solids
Authors: Böttger H. 
Published: July 2007

AbstractPhonon‐like excitations are studied on a monatomic spatially disordered system with pair interaction between the atoms. Dispersion and damping of phonon‐like excitations are governed by the self‐energy occurring in the Dyson equation of the ensemble averaged Green's function of the system. For the self‐energy a functional differential equation is derived and discussed.
Polariton line shape in two‐photon spectroscopy
Authors: Uihlein Ch. , Barentzen H. 
Published: July 2007

AbstractThe two‐photon absorption line of a polariton is derived by means of linear response theory. The shape is determined by the imaginary part of the polariton Green's function. The Green's function can be related to the complex dielectric function. The two‐photon absorption line is thus completely determined by the linear optical properties of the crystal. This is confirmed for the second exciton in CuCl were we succeeded in fitting the two‐photon line shape by means of the dielectric function known from one‐photon measurements.
Magnetoemission of GaSb: Free and bound excitons
Authors: à la Guillaume C. Benoîa , Lavallard P. 
Published: July 2007

AbstractThe free exciton g factor is measured to be equal to −9. An analysis of the magneto‐absorption and magneto‐emission data shows that the lower energy level of the bound exciton γ has Γ6 (J = 1/2) symmetry. A Jahn‐Teller effect on the acceptor site may explain this result. The bound hole g factor is evaluated to be equal to 0.3.
On the theory of the domain structure and the elastic properties of the orthorhombic weak ferromagnets
Authors: Mitsek A. I. , Kolmakova N. P. , Sirota D. I. 
Published: July 2007

AbstractThe possible magnetic states of orthorhombic weak ferromagnets and rare‐earth orthoferrites (REOF), the change of the magnetic state with the change of the temperature, and the mechanism of the formation of a new magnetic phase nucleus from a 180° domain wall for the first‐order phase transition are considered. The ΔE‐effect for both the first order phase transition and the transition by the reversible rotation of the antiferromagnetic vector and the magnetic susceptibility tensor, connected with the displacement of 90° domain walls, are calculated.
Interaction of plasma and lattice waves in piezoelectric semiconductors
Authors: Robson R. E. , Paranjape B. V. 
Published: July 2007

AbstractThe interactions between collective excitations of free electrons and holes with the lattice vibrations are investigated. Detailed calculations presented are valid in materials having piezoelectric properties. The dispersion relation is found using Boltzmann's equation for the plasma rather than the hydrodynamic equations previously used. The method followed is quite general, but is concentrated on the case where there is collisionless damping in the plasma. The case where damping of plasma waves is through collisions has been treated by Hutson and White [6]. The general formula gives their results in the limit of collision‐dominated plasma. In the collisionsless limit, it is shown that there is attenuation of lattice waves and that this reaches a maximum at a certain frequency. For frequencies slightly greater than the plasma frequency, it is shown that there can be a resonance between the optical vibrations of the plasma and the lattice waves, provided the temperature is low enough.
Calculation of nuclear quadrupole relaxation times in NaI on the basis of breathing shell model
Authors: Ray D. K. , Sangster M. J. L. 
Published: July 2007

AbstractIn order to test the accuracy of the eigenvectors associated with the ionic motions which one gets from the Breathing Shell Model (BSM) of Schröder in NaI the nuclear quadrupole relaxation times have been calculated as function of temperature at both Na23 and I127 sites and these are compared with the experimental results.
Temperature dependence of the hyperfine structure coupling parameters of CO and AsO molecule ions in γ‐irradiated single crystal calcite
Authors: Chan S. S. , Marshall S. A. , Serway R. A. 
Published: July 2007

AbstractThe hyperfine structure coupling parameters of CO and AsO molecule ions in γ‐irradiated single crystal calcite have been measured from 4.2 to 325 K. For Co, the data suggest that the fractional electron spin density at the carbon atom increases by about 1% on raising the temperature from 4.2 to 200 K. For the AsO molecule ion, the fractional electron spin density on the arsenic atom decreases by about 7% on raising the temperature from 4.2 to 325 K.
Variational method in the theory of reciprocal electron and phonon drag in semiconductors
Authors: Pinchuk I. I. , Ya. Luste O. 
Published: July 2007

AbstractA variational method of the anisotropic scattering theory is used to analyse the drag effect of electrons by phonons and of the reciprocal drag effect on the kinetic properties of semiconductors. The role of various phonon scattering mechanisms and their effect on the thermo‐e.m.f. of the drag are discussed. The temperature dependence of thermo‐e.m.f. is obtained taking into account various phonon and electron scattering mechanisms.
Binding of an exciton to a donor‐acceptor pair in a semiconductor ii. binding energy and critical separation in the case of a coulomb interaction – influence of the polarization effects
Authors: StÉabEá B. , Munschy G. 
Published: July 2007

AbstractThe binding energy of an exciton to a donor–acceptor pair is calculated in the approximation of Coulomb interactions. Haken's potential is also considered to take into account the electronic and ionic polarization effects. To this aim, the variation method is applied to an electron‐hole product wave function with two adjustable parameters. The computations are made for both equal and unequal electron and hole effective masses. The results obtained compare favourably to the experimental data in ZnSe. Haken's potential is found to be suitable for donor‐acceptor separations close to the critical length, in which case the polarization effects are still important.
Rapid variation of the superconducting transition temperature in the Al12Mg17 phase
Authors: Claeson T. , Granqvist C. G. , Ivarsson J. 
Published: July 2007

AbstractThe superconducting transition temperature decreases from about 0.7 to less than 0.03 K. as the Mg content is increased within the Al12Mg17 phase. The rapid variation is correlated with an increasing tendency for the electrons to participate in covalent and ionic bonds.
M‐Center singlet to triplet excitation in KCl
Authors: Schneider I. , Keller F. J. 
Published: July 2007

AbstractM centers are transformed to a triplet state either through the capture of an electron by an M+ center or through the optical bleaching of an M′ center. Using a technique similar to one previously developed by Schneider, Keller, and Klick, it is found that about four times as many triplets are produced through the M+ mechanism than through the M′. In these experiments, bleaching is produced with intense infrared excitation of short duration absorbed in the F′ or M′ bands for crystals which contain either M+ or M′ centers. Evidence is also presented which indicates that the M+ mechanism might be predominant at low temperatures for continuous excitation in the F‐spectral region.
Study of broadening of the NMR line due to dislocations by the monte carlo method
Authors: Plishkin Yu. M. , Greenberg B. A. 
Published: July 2007

AbstractBy the method of statistical tests (Monte Carlo) investigations were made on a digital computer of the resonance line (satellite and central line) in a crystal of the NaCl type containing edge line dislocations uniformly distributed over the volume. The expression for the frequency shift due to quadrupole interactions in the crystal containing dislocations was obtained within the framework of anisotropic elasticity. Statistical calculation of the shape of the line is made for Na23Cl and KBr81 crystals for different orientations of the magnetic field. The elementary statistical test consists in calculation of shift of frequency of a certain nucleus due to n randomly distributed dislocations. The repetition of computer experiments is carried out N times after which the whole series of experiments is subjected to statistical processing. On the basis of statistical processing of the computer experimental curves are plotted of the integral distribution function and of histograms of the probability density and calculations are made of the first moments of the resonance curve. Investigations were made of the change of the broadening of the line with the change of the orientation of the external constant magnetic field relative to the crystal having a given distribution of dislocations.
A Quantitative Study of the Stabilization Field for 180° Walls in Iron Single Crystal Sheets Containing Solute Nitrogen
Authors: Tahara Y. , Sugeno T. 
Published: July 2007

AbstractThe strength of the stabilization field for 180° walls in [100] (011) iron single crystal sheets is derived theoretically and compared with experimental results. An initial magnetization curve after the stabilization of domain walls has taken place is derived using a model in which the reversible and irreversible magnetization processes are separately taken into account. The theoretical maximum value of the stabilization field is shown to be equal to the magnetic field at which the initial magnetization curve shows a first sudden discontinuous increase in induction. Effects of domain wall orientation and magnetostriction on the strength of the stabilization field are calculated. Calculations show that the 180° walls parallel to the (011) plane can be displaced irreversibly at the weekest magnetic field. These theoretical results are satisfied by experiment. A breakaway motion of domain walls is proposed for the sudden discontinuous increase in induction in the stabilized initial magnetization curves. The flexibility of domain walls contributes to the breakaway motion of domain walls.
Density of states and conductivity in highly impure semiconductors
Authors: Lukes T. , Rogers B. A. 
Published: July 2007

AbstractThe evaluation of the density of states of a semiconductor disordered by a high density of impurities is considered by path integral methods. An effective momentum approximation and a cumulant approximation in momentum space are both used and graphical results for the density of states are presented. The results are applied to the evaluation of the static electrical mobility. It is found that this can be described by a Boltzmann like and non‐Boltzmann like term and graphical results for the variation with Fermi energy of both these terms are given.
A model of the electrical transport phenomena in imperfect crystals of copper phthalocyanine II. Surface States of Phthalocyanine Single Crystals
Authors: Hamann C. , Lehmann G. 
Published: July 2007

AbstractStarting from real grown crystals and their habit the binding energies of a molecule for different crystal directions are estimated and some ideas about the electronic surface morphology are given. The high concentration of lattice defects on the surface causes their interaction which leads to a quasicontinuous energetic distribution of traps. The microstructure of the distribution can be referred to the geometry of the crystal lattice. The theoretical results agree excellently with the experiments.
On the Theory of the Dynamic Stark Effect and Franz‐Keldysh Effect in a Resonant Electromagnetic Radiation Field
Authors: Becker L. , Enderlein R. , Peuker K. 
Published: July 2007

AbstractThe influence of the electric field of a resonant laser radiation on the dielectric function of a three‐band semiconductor model is investigated theoretically. The laser radiation is assumed to be in resonance with the transition between the two unoccupied bands of the model. The relative contributions of the dynamic Stark effect due to the interband coupling caused by the laser field and of the Franz‐Keldysh effect due to the intraband coupling are discussed. The laser‐radiation‐induced change of the real part of the dielectric function is calculated. The corresponding result for the imaginary part is in agreement with an earlier result of other authors. Explicit line shapes for the change of the real and imaginary part of the dielectric function are given with parameter values chosen close to those of GaAs.
Influence of the Size of the Precipitates in NaCl:Pb2+ Crystals on Rayleigh Scattering and UV Absorption
Authors: Fayet‐Bonnel M. 
Published: July 2007

AbstractUsing the Mie theory the extinction cross‐sections of PbCI2 spheres embedded in NaCl are calculated for various radii between 1 and 46 nm, in the wavelength region 220 to 400 nm. These calculations allow to propose a model with two types of spherical precipitates — the concentrations and the radii of which depend on the heat treatments — that fits the experimental results of UV absorption and Rayleigh scattering by NaCI:Pb2+ after different heat treatments.