International Journal of Modern Physics B

In this paper, we have synthesized meso-oxides (i.e., Co₃O₄ and NiO) by using mesoporous silica as hard template. The microstructures and chemical compositions of the corresponding meso-oxides were characterized by the Transmission electron microscope-selected area electron diffusion (TEM-SAED), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), respectively. And, their electromagnetic and microwave absorption properties were investigated in the frequency range of 2–18 GHz. The results indicate that meso-oxide templated from KIT-6 (i.e., meso-K–Co/Ni) exhibit a dual absorption characteristic compared with those using SBA-15 as hard template. This phenomenon suggests that meso-oxides templated from SBA-15 and KIT-6 can exhibit different microwave absorption behaviors due to their respective microstructures.

In this paper, we investigate the dynamical behaviors of quantum correlations witnessed by geometric discord and negativity when two three-level spin-1 atoms exist in the optical lattice. The results show that the GD can detect the critical point K = J at finite temperature associated with the quantum phase transition which separates the superfluid phase from the Mott insulator phase, while the negativity cannot. In addition, the system undergoes an entanglement sudden death (ESD), but the GD always exists, meanwhile, the GD is more robust than negativity against temperature T.

The initial stress is induced during film formation and is partially counterbalanced through curvature changes. Therefore, it is commonly evaluated by the measured residual stress. Initial stress may directly affect the film formation rather than residual stress in progressively deposited films. In the present work, we introduced a multiple layer model for progressively deposited films to obtain a quantitative solution for estimating the initial stress. The results showed that residual stress in the last layer is equal to the initial stress when layer number approaches infinity. In particular, the initial stress, σ_i in deposited film could be determined using the equation, σ_i = σ_St/β, in which σ_St is the averaged residual stress in films calculated by Stoney formula and β is the correction factor. The value of β varied between 0 and 1, depending on relative modulus and relative thickness of film and substrate. Finally, using element birth and death technique, a finite element model was presented to verify the analytical multiple layer model. Good agreement was obtained between the analytical and FE results.

The electronic structure, elastic properties, Debye temperature and thermal conductivity of MgB₂ are investigated by using the first-principles density function theory within the generalized gradient approximation (GGA). The calculated elastic constants indicate that the MgB₂ is mechanically stable. The shear modulus, Young's modulus, Poisson's ratio, σ, the ratio B/G and universal anisotropy index are also calculated. Finally, the averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature and thermal conductivity are obtained.

We show that for a multiple-connected space the low energy strain fields excitations are given by instantons, which are controlled by the phase of the superconductor. Dirac fermions with a chiral mass and a superconducting pairing field propagates effectively in a multiple-connected space. When the elastic strain field response is probed one finds that it is given by the Pointriagin characteristic. As a result the space–time metric is modified. Applying an external stress field we observe that the phonon path bends in the transverse direction to the initial direction.

The properties of sI methane hydrate dissociation at different temperatures are investigated using molecular dynamics (MD) simulations, focusing on the characteristics of structure of melting water that has memory effect. Upon melting, the clathrate structures of hydrate are damaged. The density of dissolved methane decreases as the melting temperature rises. There is a positive correlation between the density of dissociated water molecules and melting temperature. Most oxygen atoms of dissociated water molecules remain tetrahedrally coordinated whereas the hydrate-like torsion angles (H–O–O–H) are like that of normal water. Therefore, the tetrahedrally coordinated oxygen atoms are one of the factors contributing to the memory effect.

In this paper, we have proposed a step separate confinement heterostructure (SCH) based lasing nano-heterostructure In_0.90Ga_0.10As_0.59P_0.41/InP consisting of single quantum well (SQW) and investigated material gain theoretically within TE and TM polarization modes. In addition, the quasi Fermi levels in the conduction and valence bands along with other lasing characteristics like anti-guiding factor, refractive index change with carrier density and differential gain have also been investigated and reported. Moreover, the behavior of quasi Fermi levels in respective bands has also been correlated with the material gain. Strain dependent study on material gain and refractive index change has also been reported. Interestingly, strain has been reported to play a very important role in shifting the lasing wavelength of TE mode to TM mode. The results investigated in the work suggest that the proposed unstrained nano-heterostructure is very suitable as a source for optical fiber based communication systems due to its lasing wavelengths achieved at ~1.35 μm within TM mode, while ~1.40 μm within TE mode.

Density functional theory (DFT) and generalized gradient approximation (GGA) have been employed to study adsorption geometry and electronic properties of the system consisting of rutile (110) surface and dopamine molecule. Hubbard U-like term is included to consider more adequately 3d electrons of Ti atoms. Results indicate that dopamine adsorption takes place in a bidentate geometry by forming strong bonds between two molecular oxygens and two titaniums situated on the surface. Geometry changes of molecular atoms, as well as those constituting upmost layer of the surface has been discussed in detail. Reduction in the band-gap width due to the adsorption has been found implying potential interest of the system for light-harvesting solar cells.

A study of the phonon contribution to the interface properties between two bcc dissimilar solids is presented. The model system is obtained by the juxtaposition of two semi-infinite harmonic bcc lattices. The interface observables are numerically calculated for different cases of masses and elastic softening to hardening, to investigate how the local dynamics can respond to many environmental microscopic changes in the field interfacial domain. The theoretical formalism using simultaneously the Green's functions and the matching method is employed to describe the dynamics of the bcc system, the complete evanescent and the propagating fields. A calculation is presented for the vibration localized states, the coherent phonon transmission and the density of states (DOS), as element of a Landauer–Büttiker type scattering matrix.

The system dynamics, the phonon scattering and the transmission spectra via the interface domain between bcc lattices and the DOS are analyzed as function of the atomic masses and the elastic force constants occurring in the nanojunction zone of the model system.

Our results show that the interface zone is an effective phonon splitter and suggest that its characteristics may be controlled by varying its nanometric parameters. The observed fluctuations are due to the coherent coupling between continuum and discrete states induced by the interface domain.