In the last 30 days

• Open/close Raman scattering from hydrogenated microcrystalline and amorphous silicon

  Z Iqbal and S Veprek 1982 J. Phys. C: Solid State Phys. 15 377 Tag this article

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  Raman scattering measurements on hydrogenated microcrystalline silicon prepared in a hydrogen plasma at deposition temperatures between approximately=65 and 400 degrees C are presented and discussed. The shifts of the crystalline (c) and 'amorphous-like' (a) components of the spectra to lower frequencies with decreasing crystallite size have been correlated with the lattice expansion and the finite dimensions of the crystallites in these films. The roles of hydrogen and of the compressive stress in the samples have been investigated by annealing experiments and a deposition of the samples under negative bias of the substrate, respectively. These results point to a probable mechanism of the crystalline-amorphous transition in silicon. The data presented allow an assignment of the amorphous-like feature in the Raman spectra to surface-like modes at grain boundaries of the crystallites. Strong arguments are given that suggest that the 480 cm ^-1 peak in the Raman spectra of X-ray amorphous silicon is of the same origin and is hence associated with some shearing modes of Si clusters rather than a broadened density of states. Results on the depolarisation ratio of Raman scattering in the microcrystalline and X-ray amorphous films are also presented and discussed.

• Open/close Ordering, metastability and phase transitions in two-dimensional systems

  J M Kosterlitz and D J Thouless 1973 J. Phys. C: Solid State Phys. 6 1181 Tag this article

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  A new definition of order called topological order is proposed for two-dimensional systems in which no long-range order of the conventional type exists. The possibility of a phase transition characterized by a change in the response of the system to an external perturbation is discussed in the context of a mean field type of approximation. The critical behaviour found in this model displays very weak singularities. The application of these ideas to the xy model of magnetism, the solid-liquid transition, and the neutral superfluid are discussed. This type of phase transition cannot occur in a superconductor nor in a Heisenberg ferromagnet.

• Open/close 'Luttinger liquid theory' of one-dimensional quantum fluids. I. Properties of the Luttinger model and their extension to the general 1D interacting spinless Fermi gas

  F D M Haldane 1981 J. Phys. C: Solid State Phys. 14 2585 Tag this article

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  The explicitly soluble Luttinger model is used as a basis for the description of the general interacting Fermi gas in one dimension, which will be called 'Luttinger liquid theory', by analogy with Fermi liquid theory. The excitation spectrum of the Luttinger model is described by density-wave, charge and current excitations; its spectral properties determine a characteristic parameter that controls the correlation function exponents. These relations are shown to survive in non-soluble generalisations of the model with a non-linear fermion dispersion. It is proposed that this low-energy structure is universal to a wide class of 1D systems with conducting or fluid properties, including spin chains.

• Open/close Oscillatory effects and the magnetic susceptibility of carriers in inversion layers

  Yu A Bychkov and E I Rashba 1984 J. Phys. C: Solid State Phys. 17 6039 Tag this article

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  Oscillatory effects in a strong magnetic field B and magnetic susceptibility are investigated, as applied to 2D systems, in which the twofold spin degeneracy is lifted by the spin-orbit-interaction Hamiltonian H _SO= alpha ( sigma *k). nu . The term H _SO is shown to change greatly the usual patterns of B ^-1-periodic oscillations; some oscillations are strongly suppressed due to the diminishing of the gaps between adjacent levels, and new oscillations appear due to intersections of levels.

• Open/close Dielectric properties of modified PZT ceramics

  Long Wu et al 1983 J. Phys. C: Solid State Phys. 16 2803 Tag this article

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  The dependence of the dielectric constant on the electric field of PZT ceramics can be well explained by the mechanism of domain wall motion. The mobility of the domain wall is increased by the A-site vacancies, due to the reduction of local stress in the domains which undergo domain switching. But O-site vacancies and the grain boundary act as pinning points for domain walls, so the domain wall motion is reduced when O-site vacancies dominate and the grain size is small. As a result, the dielectric constant after poling was larger than that before poling and the coercive field were reduced by the addition of A-site vacancy produce. But the opposite results were obtained, when the O-site vacancy produce was added.

• Open/close Direct calculation of the tunneling current

  C Caroli et al 1971 J. Phys. C: Solid State Phys. 4 916 Tag this article

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  A simple model Hamiltonian is proposed for a metal-insulator- metal tunneling junction, which permits the direct calculation of the tunneling current without introducing any effective Hamiltonian. The model rests on the use of localized functions; this procedure avoids the difficult matching problem at the boundary between the barrier and the electrodes. Moreover the use of Kjeldysh's perturbation theory for nonequilibrium system allows an explicit calculation of the current to all orders in the applied bias. It is found that the transfer coefficient appearing in the expression for the current is energy dependent. This model can be systematically extended to include many body effects.

• Open/close Electric fields induced in alkali-containing glasses by electron irradiation

  A Miotello 1986 J. Phys. C: Solid State Phys. 19 L201 Tag this article

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  The formation of electric fields in alkali-containing glasses during electron irradiation is described by a numerical integration of Poisson's equation. The mobilities of both primary electrons and alkali ions as well as the excitation, mobility and emission of secondary electrons are considered. It is shown that during field-assisted migration of both alkali ions and electrons no transport correlation exists.

• Open/close Energy band structure of gold

  M G Ramchandani 1970 J. Phys. C: Solid State Phys. 3 S1 Tag this article

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  The energy band structure of metallic gold has been calculated by non-relativistic and relativistic augmented plane wave methods. The E( k) against k curves are plotted for some directions of high symmetry. The conduction band is an s-d mixture. The density of states curves are plotted. The results are compared with available experimental and other theoretical data on the band structure of gold

• Open/close Theory of dipole-exchange spin wave spectrum for ferromagnetic films with mixed exchange boundary conditions

  B A Kalinikos and A N Slavin 1986 J. Phys. C: Solid State Phys. 19 7013 Tag this article

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  A theory is developed for dispersion characteristics of spin waves in ferromagnetic films taking into account both the dipole-dipole and the exchange interactions. An arbitrary orientation of the internal bias magnetic field is assumed. The general case of mixing exchange boundary conditions (surface spin pinning conditions) is considered. The simple analytical dispersion equations are obtained using the classical perturbation theory. The modification of the spin wave spectrum due to surface anisotropy (or pinning conditions) is discussed.

• Open/close The critical properties of the two-dimensional xy model

  J M Kosterlitz 1974 J. Phys. C: Solid State Phys. 7 1046 Tag this article

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  The critical properties of the xy model with nearest-neighbour interactions on a two-dimensional square lattice are studied by a renormalization group technique. The mean magnetization is zero for all temperatures, and the transition is from a state of finite to one of infinite susceptibility. The correlation length is found to diverge faster than any power of the deviation from the critical temperature. Analogues of the strong scaling laws are derived and the critical exponents, eta , and delta , are the same as for the two-dimensional Ising model.