International Journal of Modern Physics B

MnSi_1.7 films with different thicknesses (16–242 nm) are prepared by magnetron sputtering and electron beam evaporation. When the MnSi_1.7 film thickness is about 40 nm or above, MnSi_1.7 films are p-type in the whole temperature range (300–700 K) in agreement with reports in literature. By co-sputtering of MnSi_1.85 and silicon targets or deposition of Si/Mn multi-layers with a larger thickness ratio, silicon is added to the films and the Seebeck coefficients transform from positive to negative with increasing temperature. The Seebeck coefficients at room temperature and 633 K are +0.098 mV/K and -0.358 mV/K, respectively. By reducing the MnSi_1.7 film thickness to 27 nm, the transition of Seebeck coefficient from positive to negative is also observed although silicon is not added intentionally. When an ultra-thin aluminum layer is deposited between MnSi_x(x < 1.7) and Si layers to enhance silicon diffusion, the p- to n-type transition temperature decreases about 100 K. The silicon-added MnSi_1.7 films usually have higher electrical resistivity.

The effect of grain boundary on the characteristics of poly-Si metal–insulator–semiconductor photodetector is investigated utilizing two-dimensional device simulator. In the investigation, the trap states in grain boundary are composed of two types: tail states and deep-level states, both of which consist of acceptor-like trap and donor-like trap. The simulation results show that the photocurrent of photodetector decreases considerably in the case of tail states above 5 ×19 cm^-3, but less susceptible to deep-level states. Furthermore, it is found that the spectral responsivities of the photodetector decrease when the energy level of acceptor-like traps shifts towards the midgap, but keep unchanged for the case of donor-like traps.

We theoretically study a ring-in-ring resonator which is coupled with a straight waveguide to yield coupled-resonator-induced transparency. Its absorption spectrum has a narrow transparency peak with respect to low group velocity, analogizing to that in electromagnetically induced transparency. The transparency peak, the phase difference between the split modes, dispersion, and group velocity can be controlled by changing reflection coefficients. Explicit expression of the group velocity at resonance are derived and discussed, the group velocity can be reached to 10⁴m/s-10⁶m/s orders of magnitude with proper choice of the parameters.

Chirality was induced in a room temperature nematic liquid crystalline mixture. The phase transitions of doped samples were studied and thermochromic response of the mixture was investigated via RGB (Red-Green-Blue) and Hue measurements.

Static and dynamic properties of matter-wave solitons in dense Bose–Einstein condensates, where three-body interactions play a significant role, have been studied by a variational approximation (VA) and numerical simulations. For experimentally relevant parameters, matter-wave solitons may acquire a flat-top shape, which suggests employing a super-Gaussian trial function for VA. Comparison of the soliton profiles, predicted by VA and those found from numerical solution of the governing Gross–Pitaevskii equation shows good agreement, thereby validating the proposed approach.

In this paper, the triangular electromagnetic resonators (TERs) is introduced and investigated. The electric mode at lower frequency and magnetic mode at higher frequency, originating from coupling to the electric field and magnetic field, are validated through the measurement in parallel-plate waveguide system, parameter retrieval algorithm and surface currents distributions. Besides, the double negative properties of TERs-wire structures have been validated through both transmission experiment and phase shift experiment. This new resonators with distinct electric resonance as well as magnetic resonance could provide us a new way to design double negative material.

A Lie algebra which consists of linear combinations of one basis of the Lie algebra A₁ is presented for which an isospectral Lax pair is exhibited. By using the zero curvature equation, the generalized mKdV equation, Liouville equation and sine-Gordon equation, sinh-Gordon equation are generated via polynomial expansions. Finally, we investigate a kind of formal Bäcklund transformation for the generalized sine-Gordon equation. The explicit Bäcklund transformation of the standard sine-Gordon equation is presented. The other equations given in the paper are obtained similarly.

We present an improved numerical implementation of the iterated perturbation theory, for use as an impurity solver for lattice models within dynamical mean field theory (DMFT). We demonstrate higher resolution of spectral and transport features and a reduced computational expense. Using this implementation, we study the issues of scaling and universality in spectral and transport properties of the particle-hole symmetric Hubbard model within DMFT. We re-examine experimental results for pressure-dependent resistivity in Selenium doped NiS₂ and thermal hysteresis on V₂O₃ and find qualitative agreement. A systematic study of spectral weight transfer in optical conductivity is carried out.

A discrete three-by-three matrix spectral problem is put forward and the corresponding discrete soliton equations are deduced. By means of the trace identity the Hamiltonian structures of the resulting equations are constructed, and furthermore, infinitely many conservation laws of the corresponding lattice system are obtained by a direct way.

This paper studies synchronization between two linearly coupled non-autonomous chaotic systems with parameter mismatches. Based on Lyapunov's stability theory and Sylvester's criterion, some algebraic criteria are derived to synchronize the master and slave system with error bound. Besides, the largest synchronization error can be estimated analytically. Some numerical examples are presented to verify the effectiveness of these criteria. In the examples, the estimated largest synchronization error is compared with the evolution of the error variable, which further shows that the present techniques are effective.

The finite size and surface roughness effects on the magnetization of NiO nanoparticles is investigated. A large magnetic moment arises for an antiferromagnetic nanoparticle due to these effects. The magnetic moment without the surface roughness has a nonmonotonic and oscillatory dependence on R, the size of the particles, with the amplitude of the fluctuations varying linearly with R. The geometry of the particle also matters a lot in the calculation of the net magnetic moment. An oblate spheroid shape particle shows an increase in net magnetic moment by increasing oblateness of the particle. However, the magnetic moment values thus calculated are very small compared to the experimental values for various sizes, indicating that the bulk antiferromagnetic structure may not hold near the surface. We incorporate the surface roughness in two different ways; an ordered surface with surface spins inside a surface roughness shell aligned due to an internal field, and a disordered surface with randomly oriented spins inside surface roughness shell. Taking a variational approach we find that the core interaction strength is modified for nontrivial values of Δ which is a signature of multi-sublattice ordering for nanoparticles. The surface roughness scale Δ is also showing size-dependent fluctuations, with an envelope decay Δ~R^-1/5. The net magnetic moment values calculated using spheroidal shape and ordered surface are close to the experimental values for different sizes.