The spectral fluctuations of random capillary wave fields appear to be intermittent. This intermittency is related to local creation and annihilation of coherent structures: ordered regions that have definite symmetry. Both the occurrence of non-Gaussian fluctuations and the existence of (quasi) long-range order question the applicability of a thermodynamic description of spatiotemporal chaos in two dimensions.

The motion of the bubble radius and of the air trapped inside the bubble during sonoluminescence are determined self-consistently by coupling the solution of the Rayleigh-Plesset equation governing the bubble radius to the solution of Euler’s equations for the motion of air in the bubble. Results are presented for three slightly different conditions of excitation, in two of which shocks are formed during the collapse of the bubble, and in which such high temperatures are attained that the air is ionized. Estimates are made of the duration and intensity of the light then radiated by the plasma.

A stability analysis is carried out for the m=1 internal kink mode, in the presence of energetic circulating particles. It is found that, including the effect of finite radial particle-orbit excursion, the m=1 internal kink mode is strongly destabilized by the resonance interaction with the energetic passing particles. Such an instability could explain the experimental observations of the ‘‘fishbone’’ oscillations during tangential neutral beam injection [W. W. Heidbrink et al., Phys. Rev. Lett. 57, 835 (1986)].

Strong Kα emission is observed in picosecond laser-plasma interactions with high-intensity-contrast, p-polarized, picosecond laser pulses. Kα emission from Si substrates overlaid with various thicknesses of Al is compared with a Monte Carlo simulation. The results show that the hot electrons which deposit their energy in the solid material have a 3-keV temperature and carry 10% of the incident laser energy. The shifted Kα emission indicates that the solid is heated to a temperature of 35 eV up to 5000 Å from the target surface, which is consistent with the preheat of the hot electrons.

High confinement mode (H-mode) discharges with peaked toroidal current density profile (high internal inductance, ${\mathit{l}}_{\mathit{i}}$) and improved confinement are obtained in the DIII-D tokamak by dynamically varying the current profile using a rapid elongation ramp technique. The confinement improvement increases with ${\mathit{l}}_{\mathit{i}}$ and persists in the presence of edge-localized modes. The plasma toroidal rotation and the corresponding radial electric field component also increase with the peakedness of the current density profile.

The question of how thermal noise should be incorporated in the continuum equations of solidification in a way which is consistent with both bulk and interfacial equilibrium fluctuations is investigated. The proper Langevin formalism which accomplishes this task is found to consist of the usual bulk forces, which remain unaffected by the presence of a two-phase boundary, and an extra stochastic force on the interface associated with its kinetics. The relevance of this force in the context of pattern formation is examined.

This paper reports observations of the intense focusing of acoustic energy that occurs along the symmetry axis in a zinc single crystal. The focusing is associated with a conical point in the wave surface and thereby the phenomenon of external conical refraction. Our observations have been obtained with (i) pointlike piezoelectric transducers (PZT) as source and detector, (ii) a focused pulsed laser source and small PZT detector, and (iii) a breaking capillary source and capacitive detector at epicenter.

High-resolution ultrasonic measurements have been performed on single-crystalline ${\mathrm{La}}_{1.86}$${\mathrm{Sr}}_{0.14}$${\mathrm{CuO}}_4$ in magnetic fields H up to 14 T. We found that by reducing temperature the transverse elastic constant (${\mathit{C}}_{11}$-${\mathit{C}}_{12}$)/2 starts to soften from about 50 K and continues to soften down to ${\mathit{T}}_{\mathit{c}}$(H), even when ${\mathit{T}}_{\mathit{c}}$(H) is reduced to 14 K by magnetic field. The softening turns to rapid hardening by the emergence of superconductivity. This behavior of C${(}_{11}$-${\mathit{C}}_{12}$)/2 is a consequence of the structural instability of the orthorhombic phase and disappearance of the instability caused by emergence of the superconducting state.

After irradiation of ${\mathrm{CaF}}_2$ single crystals with electrons in the range of 500 keV to 1 MeV we find by phonon spectroscopy with superconducting tunneling junctions phonon scattering lines at 398 GHz and 628 GHz. The line strength at 398 GHz decreases with isochronal annealing correlated with the decrease of the optical absorption at 550 nm in these samples due to Ca clusters of an average radius of 6 nm. We ascribe the 398 GHz line to acoustic resonances of these clusters and the line at 628 GHz to resonant phonon scattering at localized excitons of F- and H-center pairs.

Some highly unusual features of a lipid-water liquid crystal are revealed by high pressure x-ray diffraction, light scattering and dilatometric studies of the lamellar (bilayer ${\mathit{L}}_{\mathrm{\alpha }}$) to nonlamellar inverse hexagonal (${\mathit{H}}_{\mathrm{II}}$) phase transition: (i) The size of the unit cell of the ${\mathit{H}}_{\mathrm{II}}$ phase increases with increasing pressure; (ii) the transition volume, Δ${\mathit{V}}_{\mathit{b}\mathit{h}}$, decreases as the pressure is increased; and (iii) the intensity of scattered light increases as Δ${\mathit{V}}_{\mathit{b}\mathit{h}}$ decreases. Data are presented which suggest that this increase is due to the formation of an intermediate cubic phase, consistent with theoretical suggestions of an underlying universal phase sequence.

By measuring the complex dielectric function over 15 decades in frequency we evaluate the scaling of the α-relaxation for several glass-forming liquids including propylene carbonate. The temperature dependence of the mean relaxation time and of the relaxation strength of the relaxation function displays two dynamical regions being separated by a crossover temperature. The observed findings are essentially not in accordance with predictions of the mode-coupling theory and light scattering results for propylene carbonate [M. Elmroth et al., Phys. Rev. Lett. 68, 79 (1992)].

Previous observations of heat pulses produced by localized photoexcitation of silicon do not support the predictions of phonon ‘‘quasidiffusion’’ via anharmonic decay and elastic scattering. Our experiments, with controlled boundary conditions, verify that quasidiffusive theory is relevant in Si under very weak photoexcitation. Beyond this domain a transition to a localized source of low frequency phonons is attributed to excited carrier interactions. Photoluminescence experiments confirm the presence of electron-hole droplets coincident with this localized phonon source.

A model of a local orbital coupled through repulsive interactions to both the hybridizing and the screening channels of a conduction band is solved by Wilson’s renormalization group method. At particle-hole symmetry we find non-Fermi-liquid lines of critical points when the interaction in the screening channel is above a critical value. Away from particle-hole symmetry the system displays two stable Fermi-liquid fixed points of different symmetries, separated by a non-Fermi liquid quantum critical point, in the mixed-valence regime. The behavior in the vicinity of this point is consistent with the marginal Fermi-liquid hypothesis.

A model for the electronic structure of ${\mathrm{PrBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ is proposed with three independent components: insulating ${\mathrm{CuO}}_2$ planes with oxidation state ${\mathrm{Cu}}^{\mathrm{II}}$, mixed valent Pr ions with almost equal numbers of ${\mathrm{Pr}}^{\mathrm{III}}$ and ${\mathrm{Pr}}^{\mathrm{IV}}$, and ${\mathrm{CuO}}_3$ chains described by a t-J model with filling ≊1/2. The difference from the high-${\mathit{T}}_{\mathit{c}}$ superconductors comes from an enhanced stability of the ${\mathrm{Pr}}^{\mathrm{IV}}$ state due to hybridization with O neighbors, and involves a transfer of holes from primarily planar O 2${\mathit{p}}_{\mathrm{\sigma }}$ to 2${\mathit{p}}_{\mathrm{\pi }}$ states. The insulating nature of ${\mathrm{PrBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ is ascribed to the extreme sensitivity of the dc conductivity of the mixed valent Pr ions and the ${\mathrm{CuO}}_3$ chains to vacancies and impurities.

The thermoelectric power S of uncompensated Si:P with P concentration N near the metal-insulator transition occurring at ${\mathit{N}}_{\mathit{c}}$ has been measured at very low temperatures (0.04≤T≤3 K). For N≫${\mathit{N}}_{\mathit{c}}$, S is negative and shows the linear T dependence of a metal, whereas close to ${\mathit{N}}_{\mathit{c}}$ an anomalous behavior with a sign change of S at low T is observed. The strong dependence of S on magnetic fields up to 6 T relates the anomaly to magnetic scattering, thus giving the first experimental evidence for localized moments near the metal-insulator transition in a transport property.

We have observed a new type of magnetic linear dichroism in angle-resolved, spin-integrated photoemission: For p-polarized light under oblique incidence the Fe 3p core level peak position and line shape change when the sample magnetization is reversed. Spin-resolved measurements show that the effect is due to spin-orbit interaction in the presence of exchange interaction. The effect can be used for chemically specific diagnostics of magnetic structures.

A set of extra peaks, which dominate the region of the silver s-p band, are observed in angle-resolved photoemission from Ag islands formed on GaAs(110) by low temperature deposition and annealing to room temperature. The thickness dependence of peak spacing demonstrates that the new peaks originate from wave vector quantization due to electron confinement. The overall features of the spectra are reproduced within a model based on a superposition of emission from a distribution of island sizes, and are interpreted as quantum size effects in these small metal ‘‘quantum dots.’’

We compare the free energy computed from the ground state energy and low-lying excitations of the 2D Wigner solid and the fractional quantum Hall liquid, at magnetic filling factors of ν=1/3 and 1/5, to show that there is an experimentally accessible region of density and magnetic field where the fractional quantum Hall liquid freezes as the temperature is raised and then melts again at higher temperatures.

Polarization analysis has been used to identify the magnetic excitations in ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$. The dominant feature in the spectra is a peak at the (π,π) reciprocal lattice position and centered at 41 meV. The behavior of the peak is shown to change dramatically at ${\mathit{T}}_{\mathit{c}}$, so that the magnetic excitations responsible for the peak must be strongly coupled to the superconductivity. Below an energy of about 35 meV, superconductivity suppresses the continuum scattering found in addition to the 41-meV peak.

High-resolution electron energy loss spectroscopy has been used to investigate the energy gap (2Δ) in a series of oxygen-doped ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_{8+\mathrm{\delta }}$ single crystals with critical temperatures ranging from 71 to 94 K. Temperature dependent energy loss spectra demonstrate that 2Δ develops sharply for T<${\mathit{T}}_{\mathit{c}}$ in all of the samples, and that the magnitude of 2Δ exceeds significantly 3.5${\mathit{kT}}_{\mathit{c}}$. Furthermore, 2Δ decreases only slightly as ${\mathit{T}}_{\mathit{c}}$ is reduced from 94 to 71 K, and thus, 2Δ/${\mathit{kT}}_{\mathit{c}}$ increases systematically as ${\mathit{T}}_{\mathit{c}}$ decreases. These results indicate that ${\mathit{T}}_{\mathit{c}}$ may be reduced significantly by strong inelastic scattering in the current copper oxides.