JOURNAL OF RESEARCH ON MANY BODY SYSTEMS
Year:2015 | Volume:5 | Issue:9|Papers Count:6

In this paper we study zero bias Conductance versus temperature in a junction which is located between a Nano-wire and a d-wave superconductor. We consider superconductor in two directions: (100) and (110). Based on scattering theory we calculate zero bias conductance versus temperature and potential strength of the junction and compare our results with bulk cases. Qualitatively, our results in (100) direction don’t show any difference with bulk cases, while the difference between a Nano-wire (one dimensional metal) and a two dimensional normal metal is remarkable when superconductor is in the (110) direction. On the other hand, in two dimensional cases, zero bias conductance is an increasing function of potential strength of the junction, while our results show that it is a decreasing function which is due to the disappearance of zero bias conductance peaks.

The first-principles calculations of the structural, Elastic, and phonon dispersion properties of cubic structure of tungsten trioxide have been performed with a Generalized Gradient Approximation (GGA) and ultrasoft-pseudopotential method based on the density functional theory. The pressure dependence of the elastic constants, bulk modulus, shear modulus, Young modulus, elastic Debye temperature, elastic anisotropy factor, Poisson ratios, Ductility, elastic velocities and Kleinmann parameter are presented. An analysis for the calculated elastic constants has been made to reveal the mechanical instability of WO3 up to 150 GPa. From the phonon dispersions of WO3, it is seen that the phonon frequencies increase as the volume decreases. The results show that the lattice constant and cell volume are in good agreement with experimental results. The elastic properties of tungsten trioxide, cubic, are examined for the first time.

Including third-nearest neighbors interactions, tight-binding description of electronic dispersion reproduces the first-principle calculations for graphene as well as carbon nanotubes [S. Reich, et all, Phys.Rev. B 66, 035412 (2012)]. Using a simple tight-binding method up to the third nearest neighbor interactions and considering the orbital overlap between wave functions, the energy dispersion, the electric dipole matrix elements and the linear electric susceptibility as a function of optical frequency of some single wall carbon nanotubes for light polarized parallel to the nanotube axis are investigated. The linear electric susceptibility obtained up to the third nearest neighbors including orbital overlap is compared with those obtained for the first nearest neighbors. The calculations show a red shift in linear electric susceptibility including third neighbors in comparison with those including only first nearest neighbors.

In this work the differential and total cross section in charge transfer channel for poroton-Hydrogen In the present work the differential and total cross section in charge transfer channel has been calculated analytically for proton-hydrogen collision within first-order interaction approximation. The calculation has been done in the frame of three-body formalism to formation of atomic hydrogen from and transition at intermediate and high energy range. The scattering amplitudes have been calculated by using Fourier technique with Feynman and Nordsieck integrals at three different approximations. The results of calculation as differential and total cross section are compared with available theoretical and experimental data. It is shown that Knock-on scattering at high impact energies and large scattering angles for transition is a remarkable problem.

Magnetite nanoparticles have been synthesized using sonoelectrooxidation of iron plate in an aqueous solution of electrolyte containing thiourea as organic stabilizer. The effect of applied current on structural and magnetic properties of nanoparticles was investigated. The particles structure was characterized using XRD, and SEM.Room-temperature magnetization curves of the samples obtained using a VSM. In order to study the stoichiometric property of the magnetite nanoparticles, Mössbauer spectra in transmission geometry were recorded for all samples. The X-ray patterns showed that the products have cubic spinel structure with space group. The SEM images showed that the particles with sizes in the range 25 to 50 nm depending on the applied current are grown. The room-temperature VSM results showed that all of the samples are magnetically soft and their specific magnetization depends on the mean particle size. Mössbauer spectra are well fitted with two magnetic sextets sub-spectra corresponding to Fe3+ions at A sites (tetrahedral coordination) and Fe2.5+ ions at B sites (octahedral coordination) associated with magnetite structure.The chemical formula of samples was obtained by taking in to account the deficit of iron in their structure.

In this research thin films of FePt alloy with different percentages of iron, were electrodeposited on Cu and Au substrate in CHC mode under constant potential in single electrolytic bath.Cyclic voltametry identified the using starting voltage of deposition of alloy layers. Then, FePt/Pt multilayers with different thicknesses of platinum layers were deposited on the Cu and Au substrates. The effect of thickness on the surface morphology of the layers was studied. In this work, crystalline structure and morphology of FePt alloy and FePt/Pt multilayers have been studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Energy dispersive X-ray analysis (EDX) has determined weight and atomic percentages of the elements in the deposited layers. Magnetic properties of the alloy deposited on Au substrate have been studied using the alternating gradient force magnetometer (AGFM).