The Kolmogorov relation for the third order structure function is used to derive the energy spectrum in the far dissipation range (k→∞). This contains no unspecified constants. Using methods from matched asymptotic expansions and mild analyticity assumptions, a uniformly valid form for the inertial through the dissipative ranges is obtained. An analogous energy spectrum is presented. This is compared with the results of physical and numerical experiments on the energy spectra E(k). The theoretical predictions are found to deviate by not more than a few percent from the measured data in the entire range of wave numbers where the energy spectrum E(k) varies by more than 30 orders of magnitude.

We present a rigorous method based on the implicit function theorem for computing anomalous exponents for self-similar solutions to a variety of problems in continuum mechanics. Unlike formal perturbation methods which give only local results, our method often gives global results and analytic dependence of the exponent on parameters. We describe in detail the application of the method to source-type solutions to Barenblatt’s equation for elastoplastic flow, a problem which has been treated elsewhere by renormalization methods. We also briefly describe several other applications.

In many experiments on single-component plasmas, including antimatter plasmas, the standard diagnostic techniques used to measure the density and temperature are not appropriate. We present a new method for determining the size, shape, average density, and temperature of a single-component plasma confined in a Penning trap from measurements of the plasma mode frequencies.

The Rutherford scattering diagnostic at TEXTOR was used to determine the central toroidal rotation speed of the hydrogenic bulk ions in the plasma. During neutral beam injection speeds of the order of ${10}^5$ ${\mathrm{ms}}^{\mathrm{-}1}$ were found. With balanced injection no rotation was observed. A first comparison with Charge exchange recombination spectroscopy showed, within the accuracy of the methods, no difference in the derived speeds, in agreement with neoclassical theory. The momentum confinement time of the central hydrogenic ions was found to decrease with the neutral beam power as approximately 1/ √${\mathit{P}}_{\mathrm{NBI}}$ .

Small-angle neutron scattering experiments were performed on a polystyrene-polyisoprene diblock copolymer in concentrated dioctyl phthalate solution under Couette shear. Lamellar orientations were monitored below and above the order-disorder transition temperature with the neutron beam incident either radially or tangentially on the cylindrical shear cell. It was found that lamellae are oriented mostly parallel to the plane of the shear cell walls. Oscillatory shear helps improve the lamellar alignment. Above the quiescent order-disorder transition, the shear-induced alignment (observed as an anisotropy of the scattering ring) follows a master curve for all temperatures.

Molecular dynamics computer simulations of 10 and 20 keV Au bombardment of Au substrates were performed to elucidate the influence of surfaces on defect production. Nearly all of the damage was due to local melting and viscous flow of hot liquid onto the surface. For the 10 keV event, 554 atoms flowed to the surface, and this led to the formation of a dislocation network that extended ≊6 nm below the surface. Only three interstitial atoms, and no isolated vacancies or small vacancy clusters were produced. Loop punching and the nature of nonlinear sputtering are also discussed.

CuCl is known to exhibit large anharmonic effects and possibly a complicated multiwell Born-Oppenheimer surface reminiscent of the instabilities in perovskite ferroelectrics and cuprate superconductors. However, we have determined its phonon dispersion from first principles calculations and find it to agree well with low temperature experimental results. The calculations were carried out using a linear response formalism based on the linearized augmented plane wave method within the local density approximation. The calculated Born effective charges are within 10% of experiment and the high frequency dielectric constant ${\mathrm{\epsilon }}_{\mathrm{\infty }}$ is about 30% larger than the experimental value. This level of agreement is comparable to that attained in simpler semiconductors.

A new, generally applicable method is developed for ab initio calculation of the wave-vector dependent electron-phonon coupling. The screening of the one-electron potential is evaluated by linear-response theory using the local-density approximation and linear muffin-tin orbitals. We calculate electron-phonon coupling strengths and transport properties in Al and, for the first time, in Nb and Mo. Our results are consistent with the experimental results and are compared with previous theoretical results.

We report a high resolution synchrotron x-ray study of the first- and second-harmonic order parameter and critical fluctuation scattering at a nematic–smectic-${\mathit{A}}_2$ transition. The order parameter, smectic susceptibility, and correlation lengths for the fundamental, as well as the order parameter and smectic susceptibility for the second harmonic, yield critical exponents in good agreement with 3D-XY multicritical scaling theory. However, the second-harmonic correlation lengths disagree markedly with predictions of current theory for density wave systems.

Slips of the superfluid wave-function phase occur when the flow velocity through an aperture exceeds a critical threshold ${\mathit{v}}_{\mathit{c}}$. We propose a phase slip mechanism in which a microscopic vortex half ring is nucleated at the wall of the aperture. Its subsequent trajectory is described. The properties of the vortex close to the wall are inferred from the Gross-Pitaevskii equation and yield, at T∼0.1 K, a vortex radius at nucleation of 14 Å and a critical velocity of 21 m/s, in agreement with experiment.

We report measurements of the binding energy of dilute coverages of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ to ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ adsorbed films. These energies, when combined with measurements of the energy gap between the ground state and the first excited state of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ film, provide the binding of the excited state to the film surface. We find that for 0.1 monolayer of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ areal densities, 0.21≤${\mathit{n}}_4$≤0.53 A${\mathrm{̊}}^{\mathrm{-}2}$, the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ binding energies obtained are in reasonable agreement with values calculated using a density functional description of the film for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ coverage dependence of the binding energy.

Two molecularly doped polymer systems have been found in which the drift velocity of holes at high field strength (E) is a decreasing function of E: Molecules containing multiple electron-donor moieties dissolved at low concentration in an amorphous polymer. The most likely explanation involves geometric disorder and hopping sites that are most readily escaped by hopping against the field direction.

The first analysis of the electronic configuration at the surface of a monocrystal using low-energy positron diffraction (LEPD) is presented. This is done in conjunction with a standard structure determination for the GaAs(110) surface. Such as extension of the possibilities of LEPD is made possible by the use of the finite-difference method formalism. In addition to the improvement of the experiment-theory agreement for diffracted beam intensities, this technique provides a real cartography in three dimensions of the electronic density in the first atomic layers.

New measurements on the high-temperature superconductor ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_8$ are interpreted and found to be in quantitative agreement with a theory for electronic Raman scattering in superconductors with ${\mathit{d}}_{\mathit{x}}^2$-${\mathit{y}}^2$ pairing symmetry. The theory explains in a natural way, why the shape of the scattering intensity, as well as its change with temperature can be polarization (symmetry) dependent and hence resolves a controversy in previous interpretations of data on the electronic Raman effect.

Layered 3D high-${\mathit{T}}_{\mathit{c}}$ superconductors exhibit Kosterlitz-Thouless (KT)-like quasi-2D signatures, and a decoupling of layers for T>${\mathit{T}}_{\mathit{c}}$ has been suggested. A vortex-loop scaling approach to the layered 3D XY model, with bare anisotropic coupling ratio ${\gamma }_0^{\mathrm{-}2}$≡${\mathit{scrI}}_{\mathrm{\perp }}$/${\mathit{scrI}}_{\mathrm{\parallel }}$, shows layer fluctuations are indeed effectively decoupled,but only at finite scales a≲${\mathit{r}}_0$∼${\gamma }_0$≫1, where rectangular loops cutting single layers dominate. Finite-scale KT-like unbinding at ‘‘${\mathit{T}}_{\mathrm{KT}}$’’ (${\gamma }_0$)≲${\mathit{T}}_{\mathit{c}}$(${\gamma }_0$) yields quasi-2D signatures outside a 3D critical region ‖(T-${\mathit{T}}_{\mathit{c}}$)/${\mathit{T}}_{\mathit{c}}$‖≡‖ɛ‖=‖${\mathrm{\varepsilon }}_{\mathit{c}}$‖<${\gamma }_0^{\mathrm{-}1/\nu }$, where multilayer, elliptical tumbling loops dominate, correlated over scales ξ∼‖ɛ${\mathrm{\Vert }}^{\mathrm{-}\nu }$≫${\mathit{r}}_0$.

The mechanism of magnetic vortex motion in the classical easy-plane antiferromagnet and the vortex gas contribution to the response functions of such magnets are considered for temperatures above the Kosteritz-Thouless transition. Unlike a ferromagnet, gyrotropical properties of such vortices arise only in sufficiently strong transversal magnetic field. Because of that, the magnetic field produces an important effect on the shape and the width of the central peak of the dynamical structure factor of antiferromagnets.

The resistivity of magnetic multilayers is generally smaller when the magnetizations of successive layers are parallel, which is the so-called giant magnetoresistance or spin-valve effect. We have been able to reverse this effect and to obtain a smaller resistivity for an antiparallel arrangement by intercalating thin Cr layers within half of the Fe layers in Fe/Cu multilayers. This inverse spin-valve effect is due to the inverse spin asymmetries of the electron scattering in successive Fe layers with and without Cr. This is a confirmation of the fundamental mechanism of the giant magnetoresistance.

We study the dependence of the optic phonon Raman line shape of GaAs/AlAs multiple quantum well on photon energy and AlAs layer thickness. Broad features due to the forbidden interface modes, observed more strongly for outgoing than for incoming resonance, are induced by elastic scattering of the photoexcited exciton. The interface feature in the GaAs-like phonon region has several minima due to anticrossings of its dispersion with the odd-order confined modes. This corrects previous interpretations of these structures as due to higher even-order confined modes.

We report for the first time that doped nanocrystals of semiconductor can yield both high luminescent efficiencies and lifetime shortening at the same time. Nanocrystals of Mn-doped ZnS with sizes varying from 3.5 to 7.5 nm were prepared by a room temperature chemical process. These nanosized particles have an external photoluminescent quantum efficiency as high as 18% at room temperature and a luminescent decay at least 5 orders of magnitude faster than the corresponding ${\mathrm{Mn}}^{2+}$ radiative transition in the bulk crystals. Luminescent measurements show that the efficiency increases with decreasing size of the particles, as expected within the framework of an electron-hole localization theory. These results suggest that doped nanocrystals are indeed a new class of materials heretofore unknown.

Von Neumann’s law for 2D soap froth states that the growth rate of a bubble with n sides is proportional to n-6, and does not depend on other details of its shape. I have generalized this relation to 3D by means of an approximate geometrical model invoking maximal entropy considerations. The resulting generalized growth law is ${\mathit{V}}_{\mathit{F}}^{\mathrm{-}1/3}$${\mathit{dV}}_{\mathit{F}}$/dt=scrF(F), where F is the number of faces of a bubble of volume ${\mathit{V}}_{\mathit{F}}$, and scrF is an increasing, almost linear function, of F only. This function vanishes for F=${\mathit{F}}_0$, with ${\mathit{F}}_0$ in the range 15.7–16.1, depending on the degree of sophistication of the model. The theory reproduces fairly well a recent numerical result which indicates ${\mathit{V}}_{\mathit{F}}^{\mathrm{-}1/3}$${\mathit{dV}}_{\mathit{F}}$/dt=κ[f-(15.8±0.1)].