New Research in Physics

Abstract In this study, the Zinc Oxide nanoparticles doped with nickel and aluminum were produced by mechanochemical method. In order to investigate the structural, morphology, optical and magnetic properties of Zn_0.99-xNi_0.01Al_xO and Zn_0.97-xNi_0.03Al_xO with x= 0.01 and 0.02, the X-ray diffraction (XRD), scanning electron microscope(SEM),UV-visible spectroscopy, photoluminescence (PL) and vibrating sample magnetometer (VSM) have been used. The study of structural properties revealedthat the lattice parameters, particles and crystallite size of the nickel- doped of ZnO nanoparticles decrease with adding aluminum. The optical properties showed that the aluminum increases the optical band gap of the nickel-doped ZnO nanoparticles. The magnetic properties of the co-doped nickel-aluminum of the zinc oxide nanoparticles were measured and the results showed that at low field region (<2000 Oe) they are ferromagnetic, while at higher magnetic fields they show paramagnetic behavior

Abstract In this paper, we study the phonon transmission coefficient of a mass-spring chain including two or more electric charges by using Green’s function method within the harmonic approximation. The chain is supposed to be embedded between two simple phononic leads. To this end, the effect of Columb interaction between charges are inserted to their force constants. The results show that for the case of existence just electrical dipole in the system, the phonon transmission coefficient decreases by increasing the distance of charge positions. Moreover, the increasing the number of ions in the center chain, decreases the phonon transmission coefficient, specially, at the low and intermediate frequencies.

Abstract The study of dark energy models shows that some certain types of future cosmological singularities may appear. These singularities are classified in this paper. Using a general scalar-tensor gravity as a varying speed of light theory, we have shown that the existence of a sudden future singularity does not lead to the divergence of the speed of light. Moreover, it is possible to regularize some of the future singularities within this theory.

Abstract At the present work the ab-initio calculations based on pseudo-potential plane wave method were performed to study the structural, electronic, phononic and thermodynamic properties of GaBi compound in the stable Zinc-Blende phase. In order to investigate the role of spin-orbit interactions, in our calculations the relativistic effects have been regarded as well. Ground state parameters are computed and compared with available theoretical and experimental works. Results revealed that GaBi is a semi-metal material. Relativistic calculations suggest that GaBi has a negative band gap and these calculations to study the thermal properties of this compound is not necessary.

Abstract We study the statistical anisotropies generated in the model of hybrid inflation which is gauged under an Abelian gauge field. The model contains the inflaton field, the gauge field and the waterfall field. We are interested in the limit where the curvature perturbations are generated from inhomogeneity at the surface of end of inflation. The predictions of this model for anisotropies in scalar and tensor power spectra and their cross correlation are studied.

Abstract In this work, Co nanowires with about 43nm diameter were deposited on Alumina template using electro-deposition technique in Galvanostatic mode. The Alumina template was prepared from multistage anodizing of pure Aluminum sheet. Structural and morphology of the nanowires were investigated using x-ray diffraction technique and a scanning electron microscope. The results show that the nanowires have hexagonal structure with (002) orientation and around 45 mm length. The magnetic hysteresis loops for sample was measured in presence of magnetic field parallel and perpendicular to the nanowires axis by a vibrating sample magnetometer. The result revealed that the Co nanowires show ferromagnetic behavior at room temperature and when magnetic field applied perpendicular to the nanowires axis, the coercivity field is higher

Abstract Study of the energy distribution of hadrons produced through polarized or unpolarized top quarks can be considered as an indirect channel to search for the properties of this quark. According to the standard model of Particle Physics, top quark decays to the bottom quark and W-boson via the cascade decay mode and in the following the W-boson decays to the lepton pairs (or quark-antiquark pairs) and the bottom quark decays into an observable meson or baryon (a B-meson in most of the cases) through a hadronization process. Formerly, the energy spectrum of B-mesons produced through the polarized top quarks is studied by ignoring the polarization states of W-boson. In this paper, considering the different polarization states of W-boson, we will numerically study the angular distribution of the energy spectrum of B-mesons in a specific reference frame. Finally, we will compare this energy spectrum in two cases of polarized and unpolarized top quark.