International Journal of Modern Physics B

Recent development in the physics of high-temperature cuprate superconductivity is reviewed, with special emphasis on the phenomena of unconventional and non-universal low-energy excitations of hole- and electron-type cuprate superconductors and the possible physical origin. A phenomenology based on coexisting competing orders with cuprate superconductivity in the ground state appears to provide a consistent account for a wide range of experimental findings, including the presence (absence) of pseudogaps and Fermi arcs above the superconducting transition T_c in hole-type (electron-type) cuprate superconductors and the novel conductance modulations below T_c, particularly in the vortex state. Moreover, the competing order scenario is compatible with the possibility of pre-formed Cooper pairs and significant phase fluctuations in cuprate superconductors. The physical implications of the unified phenomenology and remaining open issues for the microscopic mechanism of cuprate superconductivity are discussed.

We propose a simple theory to explain the anomalous magneto resistance of amorphous semiconductors in the hopping regime. We derive an expression for the magneto resistance (Δρ/ρ₀), in this regime by using a reinterpretation of the effective electronic mass, velocity, and lifetime based on the density matrix approach and a three-site jump probability in topologically disordered systems. Our theory accounts for the experimental observation of (Δρ/ρ₀) for low magnetic fields at room temperature and below and supports Mott's T^-1/4 for the variable range hopping of electrical conductivity.

In this review, we present our recent results concerning accurate calculations of configurational entropy in generalized lattice-gas models. The calculations are based on the use of the thermodynamic integration method. Different applications (or systems) have been considered. Namely, systems in presence of (i) anisotropy, (ii) energetic heterogeneity, (iii) geometric heterogeneity, and (iv) multisite-occupancy adsorption. Total energy is calculated by means of the Monte Carlo simulation. Then the entropy is obtained by using thermodynamic integration starting at a known reference state. In case (iv), the method relies upon the definition of an artificial Hamiltonian associated with the system of interest for which the entropy of a reference state can be exactly known. Thermodynamic integration is then applied to obtain the entropy in a given state of the system of interest. A rich variety of behaviors is found and analyzed in the context of the lattice-gas theory.

We obtain the possible transport in an annulus filled with solid helium of which parts are of supersolidity near the interface. Our transport results qualitatively resemble those recently reported measurements.

It has been recently shown, that inhomogeneity of a multilayer structure (MS) leads to increase in sharpness of diffused-junction rectifier (see, for example, Refs. 1 and 2), which were formed in the MS. It has been also shown, that together with increasing of the sharpness homogeneity of impurity distribution in doped area increases. In this paper, both the effects (together increasing of sharpness of p–n-junction and increasing of homogeneity of impurity distribution) have been used for production of a system of a serial p–n-junctions (such as bipolar transistors). Annealing time has been optimized for increasing simultaneously the sharpness and the homogeneity.

Using an extensive series of molecular dynamic simulations on driven vortex lattices interacting with nanostructures of periodic square arrays of pinning sites of fixed density, we have obtained the B–T phase diagram representing a Bose glass to vortex liquid-phase transition. In solving the over damped equation of vortex motion, we took into account the vortex–vortex repulsion interaction, the attractive vortex–pinning interaction, and the driving Lorentz force at several values of temperature. We have found that the location of the Bose glass line (T_BG-line) depends on the pinning strength of the pinning sites. We have also found that for each pinning strength value, there is an interesting peak of the T_BG-line that occurs at the first matching field when the number of vortices equals the number of pinning sites in the sample.

Based on the single-mode laser noise model driven by quadratic colored pump noise and quantum noise with cross-correlation between real and imaginary parts of noise proposed in International Journal of Modern Physics B20, 5383 (2006) and Phys. Rev. E 73, 023802 (2006), the stochastic resonance (SR) of laser intensity is investigated by virtue of the linearized approximation. The analytic expression of signal-to-noise ratio (SNR) is calculated. It is found that the phenomena of stochastic resonance respectively exist in the curves of the SNR versus the noise cross-correlation coefficient λ_p and the SNR versus the pump parameter a, as well as the SNR versus the signal frequency for the model. It is shown that there are three different types of SR in the model: the conventional form of SR, the SR in the broad sense and the bona fide SR.

Nonreciprocal devices such as isolators are well-known in light wave communication systems. The integrated optical isolator is presented where the magnetic field modes propagate perpendicular to the in-plane magnetization of a planar magnetooptical waveguide. The cladding and film of optical isolator are made of magnetic materials with magnetization adjusted to be parallel to their plan. The substrate is filled with new artificial metamaterials (MTMs). The dispersion equation of the transverse magnetic (TM) fields is derived. The difference Δβ between the phase constant for forward and backward propagation is calculated numerically for different values of MTMs permittivity (ε_s) and permeability (μ_s). Results show that the cutoff thickness is different for forward and backward propagation and varies with the MTMs parameters. The cutoff thickness of the isolator is selected such that the coupling coefficients of the isolator with optical fiber are obviously different for forward and backward propagation.

Thermodynamic deduction and experimental results both demonstrate that gravitation causes temperature gradient in an adiabatic system, i.e., gravithermal effect: The higher altitude the lower temperature.

We elucidate the model introduced by Tuszynski et al.¹ in order to obtain more biophysically tractable results regarding the role of actin filaments in ionic transport throughout living cells.

We report a numerical study of the Taiwan stock market, in which we used three data sources: the daily Taiwan stock exchange index (TAIEX) from January 1983 to May 2006, the daily OTC index from January 1995 to May 2006, and the one-min intraday data from February 2000 to December 2003. Our study is based on numerical estimates of persistence exponent θ_p, Hurst exponent H₂, and fluctuation exponent h₂. We also discuss the results concerning persistence probability P(t), qth-order price–price correlation function G_q(t), and qth-order normalized fluctuation function f_q(t) among these indices.