Intrinsic Josephson Effect and Violation of the Josephson Relation in Layered Superconductors

Equations describing the resistive state of a layered superconductor with anisotropic pairing are derived. The similarity with a stack of Josephson junctions is found at small voltages only, when current density in the direction perpendicular to the layers can be interpreted as a sum of the Josephson superconducting, the Ohmic dissipative and the interference currents. In the spatially uniform state differential conductivity at higher voltages becomes negative. Nonuniformity of the current distribution generates the branch imbalance and violates the Josephson relation between frequency and voltage.Comment: 11 pages, no figures, revtex, to be published in Phys. Rev. Let

Early Life Relict Feature in Peptide Mass Distribution

Molecular mass of a biomolecule is characterized in mass spectroscopy by the monoisitopic mass M~mono~ and the average isotopic mass M~av~. We found that peptide masses mapped on a plane made by two parameters derived from M~mono~ and M~av~ form a peculiar global feature in form of a band-gap 5-7 ppm wide stretching across the whole peptide galaxy, with a narrow (FWHM 0.2 ppm) line in the centre. The a priori probability of such a feature to emerge by chance is less than 1:100. Peptides contributing to the central line have elemental compositions following the rules S=0; Z = (2C - N - H)/2 =0, which nine out of 20 amino acid residues satisfy. The relative abundances of amino acids in the peptides contributing to the central line correlate with the consensus order of emergence of these amino acids, with ancient amino acids being overrepresented in on-line peptides. Thus the central line is a relic of ancient life, and likely a signature of its emergence in abiotic synthesis. The linear correlation between M~av~ and M~mono~ reduces the complexity of polypeptide molecules, which may have increased the rate of their abiotic production. This, in turn may have influenced the selection of these amino acid residues for terrestrial life. Assuming the line feature is not spurious, life has emerged from elements with isotopic abundances very close to terrestrial levels, which rules out most of the Galaxy

Facing the wind of the pre-FUor V1331 Cyg

The mass outflows in T Tauri stars (TTS) are thought to be an effective mechanism to remove angular momentum during the pre-main-sequence contraction of a low-mass star. The most powerful winds are observed at the FUor stage of stellar evolution. V1331 Cyg has been considered as a TTS at the pre-FUor stage. We analyse high-resolution spectra of V1331 Cyg collected in 1998-2007 and 20-d series of spectra taken in 2012. For the first time the photospheric spectrum of the star is detected and stellar parameters are derived: spectral type G7-K0 IV, mass 2.8 Msun, radius 5 Rsun, vsini < 6 km/s. The photospheric spectrum is highly veiled, but the amount of veiling is not the same in different spectral lines, being lower in weak transitions and much higher in strong transitions. The Fe II 5018, Mg I 5183, K I 7699 and some other lines of metals are accompanied by a `shell' absorption at radial velocity of about -240 km/s. We show that these absorptions form in the post-shock gas in the jet, i.e. the star is seen though its jet. The P Cyg profiles of H-alpha and H-beta indicate the terminal wind velocity of about 500 km/s, which vary on time-scales from several days to years. A model of the stellar wind is developed to interpret the observations. The model is based on calculation of hydrogen spectral lines using the radiative transfer code TORUS. The observed H-alpha and H-beta line profiles and their variability can be well reproduced with a stellar wind model, where the mass-loss rate and collimation (opening angle) of the wind are variable. The changes of the opening angle may be induced by small variability in magetization of the inner disc wind. The mass-loss rate is found to vary within (6-11)x10^{-8} Msun/yr, with the accretion rate of 2.0x10^{-6} Msun/yr.Comment: 11 pages, 12 figures; accepted for publication in MNRAS. Typographical errors have been corrected after the proof stag

Dynamics and transformations of Josephson vortex lattice in layered superconductors

We consider dynamics of Josephson vortex lattice in layered superconductors with magnetic, charge (electrostatic) and charge-imbalance (quasiparticle) interactions between interlayer Josephson junctions taken into account. The macroscopic dynamical equations for interlayer Josephson phase differences, intralayer charge and electron-hole imbalance are obtained and used for numerical simulations. Different transformations of the vortex lattice structure are observed. It is shown that the additional dissipation due to the charge imbalance relaxation leads to the stability of triangular lattice.Comment: 9 pages, 3 eps figures, to be published in Phys. Rev.

Electron-hole imbalance in superconductor-normal metal mesoscopic structures

We analysed the electron-hole or, in another words, branch imbalance (BI) and the related electric potential $V_{imb}$ which may arise in a mesoscopic superconductor/normal metal (S/N) structure under non-equilibrium conditions in the presence of a supercurrent. Non-equilibrium conditions can be created in different ways: a) a quasiparticle current flowing between the N reservoirs; b) a temperature gradient between the N reservoirs and no quasiparticle current. It is shown that the voltage $V_{imb}$ oscillates with the phase difference $\phi$. In a cross-geometry structure the voltage $V_{imb}$ arises in the vertical branch and affects the conditions for a transition into the $\pi$-state.Comment: 6 pages, 5 figures, accepted for publication in Europhysics Letter

Surface Plasma Waves Across the Layers of Intrinsic Josephson Junctions

We predict surface electromagnetic waves propagating across the layers of intrinsic Josephson junctions. We find the spectrum of the surface waves and study the distribution of the electromagnetic field inside and outside the superconductor. The profile of the amplitude oscillations of the electric field component of such waves is peculiar: initially, it increases toward the center of the superconductor and, after reaching a crossover point, decreases exponentially.Comment: 11 pages, 5 figure

Josephson Plasma Resonance as a Structural Probe of Vortex Liquid

Recent developments of the Josephson plasma resonance and transport c-axis measurements in layered high T$_{c}$ superconductors allow to probe Josephson coupling in a wide range of the vortex phase diagram. We derive a relation between the field dependent Josephson coupling energy and the density correlation function of the vortex liquid. This relation provides a unique opportunity to extract the density correlation function of pancake vortices from the dependence of the plasma resonance on the $ab$-component of the magnetic field at a fixed $c$-axis component.Comment: 4 pages, 1 fugure, accepted to Phys. Rev. Let

Resonance effects due to the excitation of surface Josephson plasma waves in layered superconductors

We analytically examine the excitation of surface Josephson plasma waves (SJPWs) in periodically-modulated layered superconductors. We show that the absorption of the incident electromagnetic wave can be substantially increased, for certain incident angles, due to the resonance excitation of SJPWs. The absorption increase is accompanied by the decrease of the specular reflection. Moreover, we find the physical conditions guaranteeing the total absorption (and total suppression of the specular reflection). These conditions can be realized for Bi2212 superconductor films.Comment: 17 pages, 3 figure

Josephson Coupling, Phase Correlations, and Josephson Plasma Resonance in Vortex Liquid Phase

Josephson plasma resonance has been introduced recently as a powerful tool to probe interlayer Josephson coupling in different regions of the vortex phase diagram in layered superconductors. In the liquid phase, the high temperature expansion with respect to the Josephson coupling connects the Josephson plasma frequency with the phase correlation function. This function, in turn, is directly related to the pair distribution function of the liquid. We develop a recipe to extract the phase and density correlation functions from the dependencies of the plasma resonance frequency $\omega_p({\bf B})$ and the $c$ axis conductivity $\sigma_c({\bf B})$ on the {\it ab}-component of the magnetic field at fixed {\it c} -component. Using Langevin dynamic simulations of two-dimensional vortex arrays we calculate density and phase correlation functions at different temperatures. Calculated phase correlations describe very well the experimental angular dependence of the plasma resonance field. We also demonstrate that in the case of weak damping in the liquid phase, broadening of the JPR line is caused mainly by random Josephson coupling arising from the density fluctuations of pancake vortices. In this case the JPR line has a universal shape, which is determined only by parameters of the superconductors and temperature.Comment: 22 pages, 6 figures, to appear in Phys. Rev. B, December

Optical Properties of Crystals with Spatial Dispersion: Josephson Plasma Resonance in Layered Superconductors

We derive the transmission coefficient, $T(\omega)$, for grazing incidence of crystals with spatial dispersion accounting for the excitation of multiple modes with different wave vectors ${\bf k}$ for a given frequency $\omega$. The generalization of the Fresnel formulas contains the refraction indices of these modes as determined by the dielectric function $\epsilon(\omega,{\bf k})$. Near frequencies $\omega_e$, where the group velocity vanishes, $T(\omega)$ depends also on an additional parameter determined by the crystal microstructure. The transmission $T$ is significantly suppressed, if one of the excited modes is decaying into the crystal. We derive these features microscopically for the Josephson plasma resonance in layered superconductors.Comment: 4 pages, 2 figures, epl.cls style file, minor change