ab-plane tunneling and Andreev spectroscopy of superconducting gap and pseudogap in (Bi,Pb)2Sr2Ca2Cu3O10 and Bi2Sr2CaCu2O8

We have measured the temperature dependence of gap features revealed by Andreev reflection Delta_s and by tunneling Delta in the ab-plane of optimal and slightly overdoped microcrystals of (BiPb)2Sr2Ca2Cu3O10 (Bi2223) with critical temperature Tc=110-115 K, and Bi2Sr2CaCu2O8 (Bi2212) with Tc=80-84 K. The tunneling conductance of Bi2223-Insulator-Bi2223 junction shows peaks at the 2Delta gap voltage, as well as dips and broad humps at other voltages. In Bi2223, similarly to the well known Bi2212 spectra, the energies corresponding to 2Delta, to the dip, and to the hump structure are in the ratio of 2:3:4. This confirms that the dip and hump features are generic to the high temperature superconductors, irrespective of the number of CuO2 layers or the BiO superstructure. On the other hand, in both compounds Delta(T) and Delta_s(T) dependences are completely different, and we conclude that the two entities have different nature.Comment: LaTeX 2e, 17 pages, 7 figures in .eps forma

Formation of singularities on the surface of a liquid metal in a strong electric field

The nonlinear dynamics of the free surface of an ideal conducting liquid in a strong external electric field is studied. It is establish that the equations of motion for such a liquid can be solved in the approximation in which the surface deviates from a plane by small angles. This makes it possible to show that on an initially smooth surface for almost any initial conditions points with an infinite curvature corresponding to branch points of the root type can form in a finite time.Comment: 14 page

Tunable high-energy ion source via oblique laser pulse incidence on a double-layer target

The laser-driven acceleration of high quality proton beams from a double-layer target, comprised of a high-Z ion layer and a thin disk of hydrogen, is investigated with three-dimensional particle-in-cell simulations in the case of oblique incidence of a laser pulse. It is shown that the proton beam energy reaches its maximum at a certain incidence angle of the laser pulse, where it can be much greater than the energy at normal incidence. The proton beam propagates at some angle with respect to the target surface normal, as determined by the proton energy and the incidence angle

Piezomagnetism and Stress Induced Paramagnetic Meissner Effect in Mechanically Loaded High-T_c Granular Superconductors

Two novel phenomena in a weakly coupled granular superconductor under an applied stress are predicted which are based on recently suggested piezophase effect (a macroscopic quantum analog of the piezoelectric effect) in mechanically loaded grain boundary Josephson junctions. Namely, we consider the existence of stress induced paramagnetic moment in zero applied magnetic field (piezomagnetism) and its influence on a low-field magnetization (leading to a mechanically induced paramagnetic Meissner effect). The conditions under which these two effects can be experimentally measured in high-T_$ granular superconductors are discussed.Comment: 4 pages (REVTEX, epsf.sty), 2 PS figure

Chaotic Interaction of Langmuir Solitons and Long Wavelength Radiation

In this work we analyze the interaction of isolated solitary structures and ion-acoustic radiation. If the radiation amplitude is small solitary structures persists, but when the amplitude grows energy transfer towards small spatial scales occurs. We show that transfer is particularly fast when a fixed point of a low dimensional model is destroyed.Comment: LaTex + 4 eps file

On Field Induced Diaelastic Effect in a Small Josephson Contact

An analog of the diaelastic effect is predicted to occur in a small Josephson contact with Josephson vortices manifesting itself as magnetic field induced softening of the contact shear modulus C(T,H). In addition to Fraunhofer type field oscillations, C(T,H) is found to exhibit pronounced flux driven temperature oscillations near T_C

On modulational instability and energy localization in anharmonic lattices at finite energy density

The localization of vibrational energy, induced by the modulational instability of the Brillouin-zone-boundary mode in a chain of classical anharmonic oscillators with finite initial energy density, is studied within a continuum theory. We describe the initial localization stage as a gas of envelope solitons and explain their merging, eventually leading to a single localized object containing a macroscopic fraction of the total energy of the lattice. The initial-energy-density dependences of all characteristic time scales of the soliton formation and merging are described analytically. Spatial power spectra are computed and used for the quantitative explanation of the numerical results.Comment: 12 pages, 7 figure

Point contact spectroscopy of the electron-doped cuprate superconductor Pr{2-x}Ce{x}CuO4: The dependence of conductance-voltage spectra on cerium doping, barrier strength and magnetic field

We present conductance-voltage (G-V) data for point contact junctions between a normal metal and the electron doped cuprate superconductor Pr{2-x}Ce{x}CuO4 (PCCO). We observe a zero bias conductance peak (ZBCP) for the under-doped composition of this cuprate (x=0.13) which is consistent with d-wave pairing symmetry. For optimally-doped (x=0.15) and over-doped (x=0.17) PCCO, we find that the G-V characteristics indicate the presence of an order parameter without nodes. We investigate this further by obtaining point contact spectroscopy data for different barrier strengths and as a function of magnetic field.Comment: 13 pages, 9 figure