International Journal of Modern Physics B

We study memory-based random walk models to understand diffusive motion in crowded heterogeneous environments. The models considered are non-Markovian as the current move of the random walk is determined by randomly selecting a move from history. At each step, particle can take right, left or stay moves which is correlated with the randomly selected past step. There is a perfect stay–stay correlation which ensures that the particle does not move if the randomly selected past step is a stay move. The probability of traversing the same direction as the chosen history or reversing it depends on the current time and the time or position of the history selected. The time- or position-dependent biasing in moves implicitly corresponds to the heterogeneity of the environment and dictates the long-time behavior of the dynamics that can be diffusive, sub or superdiffusive. A combination of analytical solution and Monte Carlo (MC) simulation of different random walk models gives rich insight on the effects of correlations on the dynamics of a system in heterogeneous environment.

Surface plasmons supported by various metallic nanostructures have given rise to several significant breakthroughs in the field of integrated photonic devices due to its ability to effectively confine and enhance optical field in subwavelength volume. In particular, the demand to actively control optical responses of plasmonic systems becomes urgent for the miniaturization of signal processing devices, surface-enhanced Raman scattering (SERS) substrates and biochemical sensors. In this paper, we systematically investigate the plasmon modes as well as their interaction in a layered nanostructure composed of a periodically-arranged radiative nanoring and a metallic ground plane, as well as a thin insulating spacer. A tunable transparent peak on the background of the broadband plasmon resonance emerges in the reflection spectrum as changing the periodicity of nanoparticle array, a plasmonic analogue of electromagnetically induced transparency (EIT). Owing to the structural symmetry of the rings, we demonstrate a new scheme of controlling the interference between localized and delocalized plasmons by means of incident polarization and believe that the proposed metasurface may find applications in optical switching if the polarization-controlled components are introduced.

Epitaxial growth of thin films is an effective approach to minimize the contribution of bulk carriers for topological insulator (TI) Bi₂Se₃. Parameters used in preparation process are key factors for growing high quality thin films, especially for TI films. In this paper, magnetron sputtering was used for growing Bi₂Se₃ thin films on Si (100) substrates. Different working pressure and sputtering power were investigated. High-quality films could be obtained under relatively low pressure and low power. Linear and nonsaturated high-field linear magnetoresistance (LMR) was observed in high-quality films.

Single crystal copper ellipsoidal nanoshells under outer normal tensile loadings are investigated by the molecular dynamics method. Normal stress and Mises stress are introduced to describe the mechanical properties. The uniform thickness nanoshells, the variable thickness nanoshells and the variable radius nanoshells are simulated to elucidate the effect of thickness on yielding behaviors and other mechanical properties. Potential energies, stresses and dislocations of nanoshells are discussed in the paper. The dislocations of these nanoshells form an octagon or that with an external quadrangle. The variable thickness nanoshells break this shape slightly. The potential energies of nanoshells have stable stages and then increase. The outer normal stresses and Mises stresses of different models differ from eath other. The thickness of nanoshells affects the elastic stage and the variable thickness nanoshell has different mechanical properties with others. When the radiuses of nanoshells with the same thickness are different, their dislocation shapes are the pressed octagon. Thier normal yield stresses are different, but their Mises yield stress are same. Also, the outer shape determines the trend of curves. The structure of a sphere is steadier than that of an ellipsoid.

Link prediction based on topological similarity attracts more and more interests. Traditionally, researchers almost focus on utility of the paths between two unlinked endpoints, but pay little attention to the influence of the endpoints with only degree considered. Through profound investigations, we find, besides of degree, H-index and coreness also can play important roles in link prediction as the influence of endpoint especially in models based on representative SRW which is for the first time introduce influence into link prediction. In this paper, we mainly research degree, H-index and coreness in SRW-based models to explore their roles in accurate link prediction. Extensive experiments on twelve real benchmark datasets suggest that in most cases H-index serves as a better tradeoff in accurate link prediction than either degree or coreness.

AgCuZnSn filler metals were prepared from the BAg34CuZnSn filler metal by a combinative process of brush plating and thermal diffusion, and the prepared filler metals were applied to the induction brazing of the 316LN stainless steel. The corrosion behaviors of the brazed joints was evaluated based on local corrosion analyses, where the morphology of the joints was analyzed by scanning electron microscopy (SEM) after immersion in a 3.5 wt.% NaCl aqueous solution and electrolytic etching in a 10 vol.% oxalic acid solution. The microstructure of the brazed joints with the Sn-plated filler mainly consisted of the Ag phase, Cu phase, CuZn phase, Cu₅Zn₈ phase, Cu${}_{41}$Sn${}_{11}$ phase and Ag₃Sn phase. The local corrosion analysis results indicated that galvanic corrosion occurred near the interface between the stainless steel base metal and the brazing seam. With increasing local corrosion time, the corrosion rates of both the brazing seam and the base metal first exhibited an increasing trend, followed by a decreasing trend, and the corrosion rate of the brazing seam was slightly greater than that of the base metal. The corrosion behaviors analysis indicated that the corrosion resistance of the brazing seam was reduced, and concave defects emerged after electrolytic etching for 90 s.

The humidity sensor based on silicon substrate is presented in this paper, which consists of anodic aluminum oxide (AAO) film and interdigitated electrodes. By using electro-chemical oxidizing technique, AAO film with high porosity is fabricated on the silicon substrate. Under optimal oxidization condition, pore diameter of 37–79 nm and depth about $7\mu$m is achieved. Interdigitated electrodes are fabricated on the top of AAO film by vacuum evaporation deposition method. The results show that the sensor has different nonlinear response in whole range of relative humidity (RH). Moreover, it has almost linear relationship between the capacitance and RH at high RH from 75% to 95%. The highest sensitivity is obtained 613 pF/%RH at 1 kHz, which is much higher than other frequencies.

The structure of ZrB₂ under high-pressure was predicted by Particle Swarm Optimization method (CALYPSO). We investigated the structure stability, phonon dispersion curve, elasticity, electronic structure and thermodynamic properties of ZrB₂ under high-pressure and high-temperature via first-principles calculations. It maintained the hexagonal structure when the pressure lowers below 600 GPa at 0 K, which is confirmed by the calculated phonon dispersion curve. Studies indicate that the elastic modulus and Poisson’s ratio increase monotonically with pressure, as supported by some theoretical and experimental evidences. Calculated anisotropic factors demonstrate that compression and shear isotropy of ZrB₂ weakens as the pressure increases. Using the quasi-harmonic approximation Debye model, the Debye temperature, sound velocity, expansion coefficient, thermal capacity under the high-temperature and pressure were also predicted.

In this paper, structural, electronic and magnetic properties of the aluminum-rich intermetallic alloy Al${}_{13}$Fe₄ are investigated using full potential linearized augmented plane waves (FPLAPW) approach in the frame work of density functional theory (DFT). The calculated structural parameters are consistent with the experimentally reported data. In this alloy, Fe atoms possess different coordination numbers with Al atoms, i.e., Fe(1) and Fe(2) have the same coordination number 5, whereas Fe(3), Fe(4) and Fe(5) have 4, 7 and 9 coordination numbers, respectively. The compound is found metallic and ferromagnetic in nature. Post-DFT (BoltzTraP code) calculations confirm the ferromagnetic and anisotropic behavior. The Fe(5) atom plays a central role in the electronic and magnetic properties of the alloy due to the large coordination with Al atom as compared to the rest Fe atoms.

An investigation of the effect of charges of impurity on the optical properties of a hydrogenic impurity in a disk parabolic quantum dot under magnetic field has been performed by using the matrix diagonalization method. The ground state energy level becomes lower as the charges of impurity increase. The optical absorption coefficient strongly reduces with increasing charges of impurity and is strongly affected by the confinement strength, the magnetic field strength, and density of electron.

The thermodynamic properties of neon and argon gases are studied within the static fluctuation approximation (SFA). These properties include the total internal energy, pressure, entropy, compressibility and specific heat. The results are compared with those recently obtained within the Galitskii–Migdal–Feynman (GMF) formalism. The overall agreement is very good. An exception, however, is the specific-heat results for neon. While SFA gives results rather similar to those of the ideal gas, the corresponding GMF results are quite different. It is argued that the discrepancy seems to have arisen from quantum effects in conformity with very recent Monte Carlo computations. Whenever possible, our SFA results are compared to experimental data.

Alkali halides have received attention due to their potential application as detector coating. This is due to the appearance of Surface Plasmon Resonance (SPR) absorption peaks in their absorption spectrum. The formation of SPR peaks is due to the formation of cesium metal clusters within the cesium halide matrix. Experimental work on cesium iodide explained the formation of cesium clusters in cesium iodide films. It was experimentally seen that when iodine atom escapes from the cesium iodide unit cell, then the newly created cubic unit cell of cesium exerts force on neighboring cesium iodide unit cells. This force results in cesium iodide taking up a tetragonal lattice structure. The aim of this paper is to theoretically investigate the tetragonal cesium iodide’s band structure and dielectric constant using ab initio calculations. The results indicate that both the band structure and the dielectric constant of cesium iodide in tetragonal phase show a systematic variation with changes in the lattice constant. This alteration in dielectric constant or variation in refractive index of cesium iodide, which acts as the surrounding media for the cesium metal clusters, induces a shift in the SPR peak position. The calculated dielectric constants were used for Gan model calculations of the extinction coefficient and evaluation of SPR peak position (${\lambda }_{max}$). A redshift in ${\lambda }_{max}$ was seen with increasing dielectric constant that appears with stress acting on cesium iodide’s lattice. These results were found to be in agreement with experimental results reported earlier by us.

We show that the analog of de Haas–van Alphen effect (adHvA) can be generated in a two-dimensional (2D) atomic gas by the interaction between an induced electric dipole and an electromagnetic field. When the neutral atoms move in a properly designed field configuration, we have a quantization similar to the Landau levels. The effective magnetic field dependence of the oscillation amplitude of the the energy and the analog magnetization of the atomic cloud are studied. We also estimate the area of the Fermi circle of the atomic gas.