bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel self‐consistent theory of the electronic structure of inversion layers in InSb MIS structures
Authors: Zöllner J.‐P. , Übensee H. , Paasch G. , Fiedler T. , Gobsch G. 
Published: July 2007

AbstractField effect devices on the basis of InSb are increasingly used in semiconductor technique. Due to the non‐parabolicity of the band structure of the conduction band the theoretical description of such devices is more complicated than for other materials. A simple method for the self‐consistent quantum mechanical calculation of the electronic structure of inversion layers in materials with a Kane conduction band is presented which is well suited for the application in semiconductor technique. The method is based on an extension of a modified local density approximation for interface problems. The efficiency of this simple method is shown for the example of InSb by compzring with experiments and with results of earlier laborious self‐consistent calculations using wave functions. The necessity is proved to take into account the deviation from the parabolic band structure in the self‐consistent calculations.
Single crystal growth and investigation of optical and ESR absorption spectra of zirconium‐doped YAG
Authors: Asatryan H. R. , Kuzanyan A. S. , Petrosyan A. G. , Petrosyan A. K. , Sharoyan E. G. 
Published: July 2007

AbstractSingle crystals of yttrium aluminium garnet doped with zirconium ions (Y3Al5O12:Zr, YAG:Zr) are grown from the melt and their optical and ESR absorption spectra are investigated. It is established that the color centers and paramagnetic centers have an identical nature being caused by Zr3+ ions in dodechahedrical sites of the garnet lattice. The experimental results are interpreted in the approximation of crystal field and molecular orbital theories.
Quantum properties of the two‐dimensional electron gas in the n‐inversion layers of InSb grain boundaries under high hydrostatic pressure
Authors: Herrmann R. , Kraak W. , Nachtwei G. , Schurig Th. 
Published: July 2007

AbstractThe magnetotransport properties of conduction electrons in n‐type inversion layers adjacent to the grain boundary in p‐type InSb bicrystals are investigated under high hydrostatic pressure (up to 103 MPa) in magnetic fields up to 15 T. A rapid decrease of the carrier concentration in the inversion layer is observed when hydrostatic pressure is applied. From the quantum oscillations of the magnetoresistivity the characteristic parameters of the electric subbands (subband population nsi, subband energies EF — EI, and the effective cyclotron masses m*i) and their pressure dependences are established. A simple theoretical model taking into account the pressure dependence of the energy band structure of pure InSb is proposed to describe the found experimental‐data. Under high pressures and in high magnetic fields it is verified experimentally that the Hall resistivity gxy is quantized into integer multiples of h/e2.
Structural disorder model pressure‐induced transitions in Sn and semiconducting compounds
Authors: Dixit P. K. , Vaid B. A. , Sharma K. C. 
Published: July 2007

AbstractThe structure disorder model, recently proposed to explain the thermodynamic properties near the transition of first order, is generalized to include the pressure‐induced transitions in tetrahedrally coordinated tin and ANB8—N compounds (with N = 2, 3 ). For Sn the calculated values of the change in thermodynamic quantities during the transition are found to be closer to the experimental values. For ANB8—N compounds, the transition is explained in a satisfactory manner in terms of partial ionic bonds and covalent bonds. The change in compressibility near the transition is found to be in agreement with that obtained from experiments.
Bethe‐Peierls study of magnetic field induced phase transitions
Authors: Paraskevaidis C. E. , Papatriantafillou C. T. 
Published: July 2007

AbstractUsing a Bethe‐Peierls like approach the thermodynamic behavior of a two‐sublattice Ising antiferromagnet is studied focusing on low temperatures and high magnetic fields portion of its phase diagram, where the system undergoes magnetic field‐induced phase transitions. The results for the H‐T phase diagram agree quite well with those from Monte Carlo calculations and show a „peculiar”︁ boundary at low temperatures and high magnetic fields separating the AF from the PM state in which, in a certain narrow range of magnetic field values, the system undergoes an AF to PM phase transition both by increasing or decreasing the temperature at constant magnetic field. The behavior of the system is investigated in this „peculiar”︁ regime by calculating the relevant thermodynamic quantities and a qualitatively symmetric behavior at the two AF to PM transition points with respect to the two directions of temperature variation at constant field is found.
Spectral density method applied to the study of the energy spectrum of the XY model in a transverse field
Authors: Bernardes L. A. B. , Borges O. N. , Ribeiro L. A. Amarante 
Published: July 2007

AbstractThe energy spectrum of the XY model in a transverse field is studied by the spectral density method (SDM), using polar and Gaussian „ansätze”︁. Expressions for the critical temperature and critical transverse field are obtained. It is shown that, within some approximations, the static properties of this model are not modified by including damping effects in the elementary excitations.
The properties of the band spectrum parameters in the band‐inversion region of narrow‐gap Ph1−xSnxTe
Authors: Dmitriev A. I. , Lashkarev G. V. , Orletskii V. B. , Tovstyuk K. D. 
Published: July 2007

AbstractA calculation technique based on experimental data is proposed for determining the Dimmock model parameters m , P⊥,‖ of narrow‐gap Pbi−xSnxTe alloys. From the six‐band model, a relation is derived to describe the dependence of the current carrier g‐factor on carrier concentration of the alloy composition. The composition dependence of the matrix element of the momentum operator (MOME) P ⊥ as derived earlier by the authors is studied over a wide range of compositions x. The analysis of experimental data reveals an anomalous behaviour of P ⊥ in the region of band inversion. The dependence P ⊥(x) may be approximated by an exponential function. The dependences of effective masses, the g‐factor of electrons and holes, as well as mass anisotropy coefficients, on composition and carrier concentration are analyzed on the assumption that P is a function of composition. The results of the analysis are compared with experiment. It is shown that the disagreement between theory and experiment can be substantially reduced by substituting P ⊥ (x) for P ⊥ = const. Relations are given by which the carrier parameters in Pb1−xSnx Te can be calculated in terms of the Dimmock model.
Angular‐resolved X‐ray photoelectron spectra and electronic structure of SnS2
Authors: Berg U. , Chassé T. 
Published: July 2007

AbstractValence band spectra of SnS2 are measured in dependence on the polar electron emission angle. Moreover, the valence band spectra of Sp‐like electrons are calculated on the basis of two different densities of states. The possibilities but also the limits of the ARXPS with reference to a detailed comparison of measurements and calculations are shown.
A kinetic equation for polaritons
Authors: Stolz H. 
Published: July 2007

AbstractIn the framework of the Schwinger‐Keldysh formalism for nonequilibrium many‐particle systems the interaction of radiation with the electron‐hole system is considered. Spectral and kinetical properties of the photon within the system, i.e. the polariton, are investigated including the many‐body effects like phonon interaction, screening, and Pauli blocking. A kinetic equation for incoherent polaritons including the influences of these effects is presented.
Induced field at a dipole near the metal surface in the hydrodynamic approximation
Authors: Bao Tran Thoai Duy 
Published: July 2007

AbstractThe induced field at an oscillating dipole near the metal surface is derived within the hydrodynamic model. Spatial dispersion and diffuseness of the electron density at the surface are included. Numerical calculations for a rs = 2 jellium are carried out, and the image plane position is determined. Results are compared with those of Feibelman and Fuchs et al.
Inelastic scattering of electrons at the InP‐SiO2 interface
Authors: Er‐Wang Mao , Hung‐Rei Zhang , Wei‐Yuan Wang , Liang Ye , Guo‐Ping Faag 
Published: July 2007

AbstractThe negative magnetoresistance effect of the InP–SiO2, interface is investigated. The results indicate that the inelastic interaction of electrons with polar optical phonons plays an important role in the inelastic scattering process of the system.Es wird der negative Magnetowiderstandseffekt an der InP‐SiO2‐Grenzfläche untersucht. Die Ergebnisse zeigen, daß die inelastische Wechselwirkung der Elektronen mit polaren optischen Phononen eine wesentliche Rolle im inelastischen Streuprozeß des Systems spielt.
The Electronic Energy Bands of AgN02 Crystal at Room Temperature
Authors: El‐Dib A. M. , Hassan H. F. 
Published: July 2007

AbstractThe electronic energy bands of AgNO2 crystals are calculated at room temperature in different directions. The calculations are carried out using a semiempirical LCAO method. The Madelung potentials at different lattice sites are also calculated. The general features of the electronic energy bands of AgNO2 are similar to those of NaNO2 in its ferroelectric phase. The minimum indirect energy gap (Eg) equals to 2.522 eV, and occurs in the R‐T direction.
Energy Band Structure Calculations for Crystals with Spiral Magnetic Structure
Authors: Sandratskii L. M. 
Published: July 2007

AbstractA generalization is given of three the most universal methods of energy band structure calculations (KKR, APW, and tight binding) in the case of crystals with noncollinear spin configuration. It is shown that the use of generalize dsymmetry allows in many physically interesting cases to deduce a secular equation, which dimension is only two times higher than the dimension of the secular equation for a collinear magnet with the same crystal lattice. The possibilities of the methods are illustrated by a model example.
GME and the Electron or Exciton Initial Condition Term Due to Lattice Relaxation Dimer
Authors: Čápek V. 
Published: July 2007

AbstractInstantaneous creation of an electron or exciton in a dimer interacting with initially statistically independent unrelaxed lattice phonons leads to an initial condition term in the time‐convolution generalized master equations (GME) for the site occupation probabilities which may be undamped with increasing time till the coherence decay time provided the finite exciton‐lifetime effects are negligible. For the Peier form of the projector diagonalizing the full density matrix in the small polaron representation with the canonical form of the reference phonon density matrix and temperature equal to that of the initially unrelaxed equilibrium harmonic phonons, this term is calculated to the second order in the relevant hopping integral and its magnitude is estimated.
A Reformulation of the LUC‐CNDO Approach to the Properties of Solids. Application to Diamond and Silicon
Authors: Smith P. V. , Szymanski J. E. , Matthew J. A. D. 
Published: July 2007

AbstractA modified version of the periodic large unit cell (LUC) approach, using the semi‐empirical complete neglect of differential overlap (CNDO) molecular orbital method is applied within the k = 0 approximation to the properties of diamond and silicon. The modified formalism is shown to be capable of producing good results for the properties of the perfect crystal and its capabilities for the study of systems of lower symmetry, such as defects or surfaces, is discussed.
ODMR in Triplet Excited States of ns2 Ions in Alkali Halide Crystals
Authors: Baranov P. G. , Vetrov V. A. , Romanov N. G. , Topa V. 
Published: July 2007

AbstractOptically detected magnetic resonance (ODMR) is applied for the first time to the investigation of triplet relaxed excited states (RES) of divalent ns2 ions in alkali halide crystals. Four types of ODMR spectra related to the RES of Ge2+ are found. Spectral and angular dependences of ODMR are studied. ODMR data on the RES of monovalent (Ga+) and divalent (Ge2+) ns2 ions are discussed. These results provide the first experimental evidence of the effect of nuclear charge on the wavefunction density distribution for excited states of impurity ions in crystals.
Optical Properties of Metals: Au
Authors: Jungk G. , Röseler A. 
Published: July 2007

AbstractThe dielectric function of Au films is determined ellipsometrically in the wave‐number ranges 700 cm−1 ≦ v ≦ 1900 cm−1 and 2500 cm−1 ≦ v ≦ 3000 cm−1 as well as for 8900 cm−1 ≦ v ≦ 32300 cm−1 (1.1 eV ≦ ħω ≦ 4 eV). The spectra are discussed taking into account intra‐ and interband transitions. An energy‐dependent plasma frequency and damping is found. The sample effects are essentially described within an effective medium approximation assuming the influence of voids. Some peculiarities of the frequency dependence of the damping parameter are likely due to the influence of fractals.
Position and Lifetime of Photoluminescence in Cd1−xMnxTe and Zn1−xMnxTe. Exchange Dependent Effects
Authors: Müller E. , Gebhardt W. 
Published: July 2007

AbstractData on position and lifetime of the photoluminescence band in Cd1−xMnxTe and Zn1−xMnxTe are reported for different manganese concentrations x. The luminescence is due to intraatomic transitions within the manganese ions. The blue shift at low temperatures shows the typical behavior of an exchange dependent parameter. The lifetimes are in the microsecond range. At low temperatures the decay is dominated by the radiative lifetime with weak temperature dependence. In Zn1−xMnxTe the lifetime varies with manganese concentration, whereas in Cd1−xMnxTe the concentration dependence is insignificant.
Structural Disorder Model for Amorphous Semiconductors: a‐Se
Authors: Vaid B. A. , Sharma K. C. 
Published: July 2007

AbstractThe structural disorder model, recently proposed by the authors, for amorphous semiconductors is generalized for Se within the framework of the concept of charged dangling bond (CDB) defects, packing fraction, thermodynamic theory of defects, and the additive approximation near the crystalline to amorphous transition which is interpreted as a point of spontaneous production of CDB defects. The model is able to explain at least qualitatively the data on thermodynamic properties, the structural disorder parameter X representing the ratio 〈U2〉x/〈U2〉0, and the width of the Urbach absorption edge E0(T, X).
Monte Carlo Simulation of Electron–Phonon Scattering in the XUV‐Induced Electron Emission of NaCl
Authors: Ausmees A. , Elango M. , Kikas A. , Pruulmann J. 
Published: July 2007

AbstractA Monte Carlo simulation of the electron emission induced in NaCl by 60 to 250 eV photons is carried out. The number as well as the initial energy and spatial distribution of conduction electrons, obtained in a previous paper, are used as the input. Electron–phonon scattering events are treated semiclassically. Optical as well as acoustical phonons are taken into account, so that with the increase of electron energy the scattering probability decreases for optical and increases for acoustical phonons. The parameters of the model are adjusted to fit the experimental quantum yield and energy spectra of emitted electrons. It appears that for high‐energy (>2 to 3 eV) electrons the electron–phonon scattering is mainly due to acoustical phonons.
Theory of the Infrared Spectrum of Size‐Quantized Bi Films
Authors: Zaluzny M. , Lukasik A. 
Published: July 2007

AbstractThe influence of the intersubband transitions on p‐polarized infrared spectrum of size‐quantized Bi films with normal along trigonal axes is investigated. The optical conductivity is evaluated using the two‐band model. Results indicate that contrary to Cottey's theory the absorption lines connected with intersubband transitions are very weak.
On the Theory of Partial and Total Internal Reflection of a Plane TM Wave from Symmetrically Realigned Nematic Liquid Crystal Layers
Authors: Hinov H. P. 
Published: July 2007

AbstractThe influence of the leading term in the exact solution of the Maxwell equations on the reflection of a plane TM wave from a symmetrically realigned nematic layer with tangential orientation at the limiting walls and arbitrary anchoring is considered theoretically. The reflectivity coefficient R is obtained and the possibilities for application in the experiments eventually performed are discussed in detail. On the basis of the theoretical results obtained, the case of a symmetrically deformed homoeotropic nematic layer is briefly considered as well.
Force Sum Rules at Surfaces
Authors: Kaschner R. , Ziesche P. 
Published: July 2007

AbstractHellmann‐Feynman theorems for partially extended arrangements of atoms are derived and applied to one‐, two‐, and three‐dimensional solids. The derivatives of the bulk energy with respect to the lattice spacings are related to the Hellmann‐Feynman forces in the corresponding semi‐infinite unrelaxed solids. These forces have to alternate going from the surface into the bulk provided that the latter is in equilibrium.
Dynamical Structure of Alpha Helical Proteins
Authors: Ichinose S. 
Published: July 2007

AbstractVibrational structures of a vibron soliton are studied in terms of the classical vibron model of the α‐helical protein molecule. It is shown that the dynamical structures of the α‐helical protein molecule are described by three types of internal oscillations of vibron solitons which are governed by a set of coupled nonlinear Schrödinger equations.
A Self‐Consistent Theory of Phonon‐Like Excitations in Structurally Disordered Solids
Authors: Wegener D. , Böttger H. 
Published: July 2007

AbstractMaking use of a Green function technique, on the basis of the model of a “frozen‐in hot crystal” a self‐consistent theory of elementary excitations in structurally disordered solids is developed. The theory provides a Green function which is analytical in the whole frequency range. It is used for evaluating dispersion and damping of phonon‐like excitations in a one‐dimensional structurally disordered model.
Fourth‐Order Thermal Expansion for Cubic Solids. Application to Aluminum, Copper, Germanium, and Silicon
Authors: Delannoy‐Coutris M. , Perrin G. 
Published: July 2007

AbstractThe fourth‐order anharmonic finite‐strain theory leads to a model for the volume dependence of the Grüneisen parameter and simultaneously to a Mie‐Grüneisen equation of state. These relations are used to derive the fourth‐order expressions for the thermal expansion coefficient of cubic crystals. A comparative study of the results with experimental data is given for the temperature dependence of the linear thermal expansion coefficient α of aluminum, copper, germanium, and silicon. It is shown that the theory agrees with experiment even better since the Grüneisen coefficient can be reasonably assumed to be temperature independent. Finally, an estimation of the variation of the thermal expansion coefficient with volumetric compression is given for aluminum, copper, germanium, and silicon using both, the Lagrangian and Eulerian strain measures.
Solitary Excitations in Molecular Chains Due to the Anharmonicity of the Intramolecular Vibrations
Authors: Primatarova M. T. 
Published: July 2007

AbstractSolitary excitations in molecular chains are theoretically investigated in the presence of intramolecular vibrations of one and the same type and of two different types. In both the cases the solitary bound formations are obtained to exist as a result of the anharmonicity of the intramolecular vibrations. It is found that solitary formations can exist and propagate along the chain also in the case when in addition the chain molecule motions are taken into account. The parameters of the solitary excitations (length, energy) are calculated.
Rate‐Equation Treatment of PAC‐Monitored Defect Reactions in Irradiated Metals
Authors: Golczewski J. , Frank W. 
Published: July 2007

AbstractThe variations of the fractions of defect‐occupied PAC probe atoms in low‐temperature electron‐irradiated metals during isochronal annealing up to the completion of recovery stage III are computer‐simulated within the framework of a rate‐equation approach. It is taken into account that the Stage‐IE interstitials migrate three‐dimensionally in the one‐interstitial model (OIM) but one‐dimensionally in the two‐interstitial model (TIM). The effect of the thermal conversion o crowdions and the existence of “caged” crowdion–PAC‐atom pairs, which are characteristic of the TIM, are investigated in detail. A comparison with experimental data shows that several observations may be understood in terms of the TIM but not of the OIM.
The Theory of Dynamic Annihilation of Dislocations
Authors: Kusov A. A. , Vladimirov V. I. 
Published: July 2007

AbstractA mechanism is proposed of the rapid annihilation of mixed dislocations by means of the cross‐slip of the double kink on the screw segment of the dislocation. The maximum annihilation distance R between dislocations as a function of applied stress σ, dislocation friction stress σ0, and angle α between the dislocation line and the Burgers vector b is correctly calculated. The comparison is made of theoretical results with available experimental data and previous rough theoretical estimations. It is shown that the annihilation mechanism is weakly connected with thermal fluctuations and it mainly has a pure force nature.
Dielectric Response of Some Semiconducting TCNQ Salts in the Submillimetre Range
Authors: Gorshunov B. P. , Kozlov G. V. , Volkov A. A. , Petzelt J. , Železný V. 
Published: July 2007

AbstractThe complex permittivity spectra of the semiconducting salts MTPA(TCNQ)2, MTPP(TCNQ)2 and of the semiconducting phases of MEM(TCNQ)2 are measured for the first time in the 8 to 30 cm−1 range and in the temperature interval 5 to 350 K for polarization parallel and perpendicular to the conducting stacks. In the case of parallel polarization the model of interrupted conducting strands is used to assign the spectra, where individual tetramers are taken as the strands. In the case of perpendicular polarization the conductivity spectra can be understood as due to hopping conductivity with a broad distribution of relaxation times.
Impurities in Ni3Fe Magnetic Alloys
Authors: Matysina Z. A. , Mekhrabov A. O. , Menshikov A. Z. , Babaev Z. M. , Zaginaichenko S. Yu. 
Published: July 2007

AbstractAn expression for the order–disorder transformation temperature in substitutional alloys of AB3‐type is determined in terms of the classical theory of ordering in alloys with low impurity concentration. The order–disorder transformation temperature is shown to increase at the initial stages of alloying at any relations of ordering energies. The data on theoretical calculations are compared with experimental ones obtained with Ni3Fe alloy doped by different impurities. Much consideration is given to results obtained with Ni3(Fe1−xMnx) alloys. Using neutron diffraction analysis, the lack of Ni24Fe4Mn4 ternary superstructure is shown, and the TK(x) dependence with the extremum at x ≈ 0.4 is obtained from dilatometric and specific heat measurement.
Thermodynamic Features of the System of Packed Antiferroelectric Chains
Authors: Kholopov E. V. 
Published: July 2007

AbstractThe system is considered of Ising‐like chains suffering the antiferroelectric instability. The interaction between the chains is taken into account within the framework of the molecular field approximation. Then summing over states of a single chain is carried out by the method making immediately use of the fact that the unit cell can consist of several atoms. Such an approach may sometimes be more convenient than the transfer‐matrix method. An appropriate phase diagram in an uniform external field is investigated. As a result, the electrical effects essentially must be small so that the corresponding measurements will be difficult in such systems. As an example the TlHF2 structure is discussed.