Modern Physics Letters B

Since the discovery of cuprate superconductors, the mechanism of high temperature superconductivity is still a mystery. Among the investigation tools, the electronic Raman scattering is a powerful one to probe electronic excitations in different regions of the Fermi surface of cuprate superconductors by a simple choice of the incident and scattered polarization vectors. Thus the symmetry of the superconducting Cooper pairs can be indicated. In this article we review our investigations of electronic Raman scattering in cuprate superconductors based on the t–J model within the kinetic energy driven superconductivity. The theory of electronic Raman response in cuprate superconductors is presented together with an overview of the charge-spin separation fermion-spin theory to handle the t–J model. Some theoretical results of electronic Raman response are presented in comparison with the experimental results. Special emphasize is given to the doping and temperature dependent of electronic Raman spectra.

Synthesis of Cobalt nanoparticles often entails toxic and expensive physical-chemistry methods. Fabrication of pure cobalt nanoparticles (NPs) using a simple and low-cost electric arc discharge method in ethylene glycol (EG) is suggested for the first time. The effect of different arc discharge currents (10, 20 and 30 A) on the size and optical absorption of the NPs are studied. Dynamic light scattering (DLS) and UV-visible spectroscopy result indicate that at an arc current of 10 A NPs of about 92.95 nm are produced and increasing the arc current leads to larger NPs. UV-visible spectroscopy data shows that the solvent gets more and more transparent with time. Sonication proves that this effect is related to agglomeration of the NPs. Formation of the pure Co NPs are evidenced by means of X-ray diffraction (XRD) measurements which gives an average size of about 21 nm using Scherrer's relation. Magnetization measurements of the samples are carried out by Alternating Gradient Force Magnetometer (AGFM). The results demonstrate the ability of the arc discharge method for direct formation of Co NPs in EG medium.

Based on the quantum theory and a simplified version of the multiple-scale method, the nonlinear excitations in a two-dimensional ferromagnetic lattice with an external magnetic field are analytically investigated. The standard two-dimensional nonlinear Schrödinger equation is obtained. Results show that the quantum quasi-soliton can exist in the two-dimensional ferromagnetic lattice. In addition, when the group velocity is equal to zero, at the boundary of the Brillouin zone, the quantum quasi-soliton becomes the quantum intrinsic localized mode.

In this paper, we report a novel CdS nanobelt formed by nanoparticles and prepared by an accurately designed thermal-evaporating method. The CdS nanobelts present single-crystalline characteristic and their zone axis was along crystal direction. Based on TEM images, a proper growth mechanism of CdS nanobelts is proposed. The growth of CdS nanobelts follows three steps: (a) CdS nanoparticles with the diameter of ~ 3 nm were formed by reaction of Cd and S atoms at high temperature, (b) nanoparticles aggregated along several specific crystal directions ( and [0001]) and nanobelt with planar surfaces were formed by an oriented attachment growth, (c) nanoparticles were continuously grown on the surface of nanobelt via a homo-epitaxial route. Two Raman peaks (at 299.0 cm^-1 and 603.5 cm^-1) of the CdS nanobelts shift toward lower frequency compared with the reported works. A symmetrical intensive peak centered at 2.43 eV was observed in PL spectrum of CdS nanobelts. These novel CdS nanobelts show favorable optical emission properties and are promising candidates for future applications in optoelectronic nanodevices.

Thermoelectric and thermomagnetic properties of graphene are analyzed using Boltzmann transport equation within the relaxation time approximation. Influence of temperature, charge carrier density and magnetic field on the thermopower and figure of merit is taken into account in the presence of different scattering processes. It is observed the magnetic field results in the increase of thermopower and figure of merit in the acoustical phonon scattering process, while they are reduced by charged impurity scattering.

We hereby are reporting the transition pressure at which lithium fluoride (LiF) compound transforms from direct band gap to indirect band gap insulator on the basis of FP-LAPW calculations. The fundamental band gap of LiF compound suffers direct to indirect transition at a pressure of 70 GPa. The study of the pressure effect on the optical properties e.g. dielectric function, reflectivity, refractive index and optical conductivity of LiF in the pressure between 0–100 GPa, shows that this pressure range is very critical for LiF compound as there are significant changes in the optical properties of this compound.

In this paper, theoretical analysis and extensive simulations are used to investigate asymmetric simple exclusion processes (ASEPs) with zoned inhomogeneity and on-ramp in a single-lane system. There are five possible phase diagrams with different hopping rate p and on-ramp rate q. Interestingly, the MC/MC, MC/LD and MC/HD phase can exist in the phase diagram with different hopping rate p and on-ramp rate q. When the on-ramp rate is fixed, with the decreasing of hopping rate, the HD/HD phase shrinks, it implies the heavy traffic in the system.

In this paper, we investigate particle traffic on an m-input n-output (MINO) junction using totally asymmetric exclusion processes (TASEPs) under random sequential update. The model is suitable for description of biological transport. A general theoretical solution for traffic dynamics of TASEPs is developed based on a mean-field approximation. It is found that the low-density and high-density regions can be calculated qualitatively and quantitatively once the number of m and/or n is determined. The phase diagram, system current and density profiles are obtained through theoretical analysis and supported by Monte Carlo simulations. Comparison between a m-input n-output TASEP junction in random and parallel sequential updates has also been reported.