International Journal of Modern Physics B

A new fractional order chaotic n-scroll modified Chua circuit is introduced. It can generate n-scroll with a total order less than three. The equilibrium points are classified into two types according to the characteristics of the eigenvalues of the Jacobian matrix at the equilibrium points. To overcome some disadvantages of the traditional fractional order controller, a new fractional order control method is developed for stabilizing the system to any expected equilibrium point. Numerical examples are provided to verify the effectiveness of the proposed scheme.

We evolve an effective interionic interaction potential (EIoIP) to investigate the pressure induced phase transitions from Zinc blende (B3) to Rocksalt (B1) structure in ZnSe semiconductor. The developed potential consists of the long-range Coulomb and three-body interactions (TBI) and the Hafemeister and Flygare type short-range (SR) overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction. The three-body interactions arise from the electron-shell deformation when the nearest-neighbor ions overlap and has been employed for detailed studies of pressure-induced phase-transition behavior of ZnSe semiconductors. Our calculated value of the phase transition pressure (P_t) is higher and the magnitude of the discontinuity in volume at the transition pressure is consistent with reported data. The variation of second-order elastic constants with pressure resembles that observed in some binary semiconductors. It is inferred that the vdW interaction is effective in obtaining the Debye temperature, Gruneisen parameter, thermal expansion coefficient and compressibility. It is argued that the model with TBI (model II) has yielded somewhat more realistic predictions of the phase-transition and high-pressure behavior as compared to usual two-body potentials (model I) based on phenomenological approach.

There are some issues such as tunneling, leakage currents and boron diffusion through the ultra thin SiO₂ which are threatening ultra thin SiO₂ dielectric as a good gate dielectric. A very obvious alternative material is HfO₂, due to its high dielectric constant, wide band gap and good thermal stability on silicon substrate. We have thus demonstrated a number of processes to synthesize La₂O₃/HfO₂ and studied its nano structural properties with using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The obtained results show that La₂O₃/HfO₂ (at 500°C with amorphous structure) can be introduced as a good gate dielectric for the future of complementary metal insulator semiconductor (CMIS) device.

Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO₃ is still not fully understood. In this paper, nanoparticles of Ba_xSr_(1-x)TiO₃ (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Ba_x Ti_1-xO₃ in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

The periodic modulation on dynamic behavior of Bose–Josephson junction dispersively coupled to a single mode high-finesse optical cavity is investigated. The eigenenergies and the phase diagram of the system are obtained using the numerical methods under the mean field approximation. It is shown that the large atomic interaction strength will lead the eigenenergies to show a bistable and a loop structure. It is also found that the periodic modulation can change the period and frequency of the motion of the atoms and the intra cavity photons drastically. Furthermore, the strong condensate-field interplay will enhance the oscillation of the atoms and make some trapped atoms start oscillating. For certain parameters of the cavity field, the relative population oscillation exhibits a process from order to chaos.

We investigate the configuration of gel sheets with centrosymmetric distribution of monomer concentration in this paper. The configuration energy of these gel sheets consists of the in-plane stretching energy and bending energy. The equilibrium shape equations are derived by variation principle. This provides a way to control the shape of gel sheets by the initial concentration and thickness. From the equilibrium shape equations, we know that the Gaussian curvature on boundary (K|_C) of equilibrium shape is determined by the Poisson ratio . K|_C is negative when but positive when . Specially, we derive two dome-like solutions from the equilibrium shape equations to compare with the experimental data. In these dome-like sheets, on the boundary part the Gaussian curvature is K < 0, which is different from the center part (K > 0). Furthermore, we deduce that the initial gel distribution of cylinder sheets is proportional to 1/r and find that N-isopropylacrylamide cylinder sheets cannot be formed without additional edges. Our theoretical results agree well with the experimental data [Klein et al., Science315, 1116 (2007)]. On the other hand, we predict a special type of gel sheets as minimal surface. Their residual stresses are constant and same along radial and circumference directions. For axisymmetric sheets, we give a criterion about the sign of Gaussian curvature K when thickness h is infinite small.

In this paper we present a simple approximate transfer matrix method for 2D and 3D hyper cubic nearest neighbor Ising models with various coordination number z to calculate the corresponding critical coupling strengths K_c. The critical coupling strengths of the Ising ferromagnets are obtained quite accurately by simple improvements over the self-consistent correlated field (SCCF) approximation. The important physical effect included in this work is some of the fluctuation effects of the systems by the help of a reduced transfer matrix method. When used in combination with the accuracy of the average magnetization obtained from the SCCF approximation, this reduced transfer matrix method leads to estimate of K_c more accurate than those obtained from the Bethe–Peierls–Weiss approximation and also SCCF approximation. Therefore, we believe that the approach we refer to as the correlated reduced transfer matrix method is potentially very useful scheme for obtaining approximate values of the critical coupling strengths of the Ising models with a mathematically easy meaner.