Modern Physics Letters B

Paramelaconite (Cu₄O₃) is a metastable copper oxide. Metastable copper oxide thin films were deposited on glass substrates by reactive RF magnetron sputtering in argon (Ar) and oxygen (O₂) gas mixture atmospheres. Ar/O₂ gas ratios in the sputtering ambient were chosen as 1/1 and 1/9. The surface and optical properties were determined by X-ray diffractometer (XRD), atomic force microscope (AFM) and UV-Vis spectrophotometer. The XRD patterns of the samples exhibited single strong diffraction peaks at 35.39${}^{\circ }$ and 35.49${}^{\circ }$, corresponding to the (202) peak of Cu₄O₃. The mean thickness values were measured as 100 nm and 80 nm for the films deposited at 1/1 and 1/9 Ar/O₂ gas ratios, respectively. The samples showed low transmittance and high absorbance in the high frequency region.

Investigation is given to a forced generalized variable-coefficient Korteweg–de Vries equation for the atmospheric blocking phenomenon. Applying the double-logarithmic and rational transformations, respectively, under certain variable-coefficient constraints, we get two different types of bilinear forms: (a) Based on the first type, the bilinear Bäcklund transformation (BT) is derived, the $N$-soliton solutions in the Wronskian form are constructed, and the $(N-1)$- and $N$-soliton solutions are proved to satisfy the bilinear BT; (b) Based on the second type, via the Hirota method, the one- and two-soliton solutions are obtained. Those two types of solutions are different. Graphic analysis on the two types shows that the soliton velocity depends on $d(t)$, $h(t)$, $f(t)$ and $R(t)$, the soliton amplitude is merely related to $f(t)$, and the background depends on $R(t)$ and $f(t)$, where $d(t)$, $h(t)$, $q(t)$ and $f(t)$ are the dissipative, dispersive, nonuniform and line-damping coefficients, respectively, and $R(t)$ is the external-force term. We present some types of interactions between the two solitons, including the head-on and overtaking interactions, interactions between the velocity- and amplitude-unvarying two solitons, between the velocity-varying while amplitude-unvarying two solitons and between the velocity- and amplitude-varying two solitons, as well as the interactions occurring on the constant and varying backgrounds.

Competitive services have large effects on traffic congestion. Based on the investigation on Chinese railway network, a competitive services model is proposed to capture traffic correlations between different services. According to the value of the weight parameter $𝜃$, competitive services are grouped into assortative, disassortative and neutral ones, in which their traffic loads show strongly positive, weakly positive and non-significant correlations, respectively. Simulation results illustrate that our model can effectively capture the service correlations by adjusting the weight parameter. Using this model, we analyze the influence of different types of competitive services on network congestion. Our results indicate that both capacity and efficiency of network is the lowest when it supports assortative services.

In this paper, all solution processing is used to prepare both the transparent conducting Ba${}_{0.92}$La${}_{0.08}$SnO₃ (BLSO) thin films as bottom electrodes and ferroelectric Bi₆Fe₂Ti₃O${}_{18}$ (BFTO) thin films. The derived BFTO thin films are characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The derived thin film is polycrystalline with dense microstructures. The remnant polarization $2P_r$ at the measurement frequency of 2 kHz can reach $\sim 16.8\mu {\mathrm{\text{C/cm}}}^2$ under the 500 kV/cm electric field and the coercive field $2E_c$ is 410 kV/cm. The results will provide a feasible route to prepare BFTO thin films on transparent conducting bottom electrodes to realize multifunctionality.

The electron mobility of the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with the ratio of the gate length to the drain-to-source distance being less than 1/2 has been studied in the temperature range 100 $\sim$ 300 K. The measured electron mobility at each testing temperature is obtained by using the capacitance–voltage (C–V) and current–voltage (I–V) characteristics measured at the corresponding temperature, and the theoretically calculated temperature-dependent electron mobility is determined by Matthiessen’s law, which includes five kinds of important scattering mechanisms. For the prepared sample, the measured electron mobility with respect to the two-dimensional electron gas (2DEG) density was observed to increase to a peak point first and then decrease at each testing temperature. By comparing the measured electron mobility with the theoretically calculated value, the changing trend of the electron mobility at each testing temperature was found to be mainly determined by polarization Coulomb field (PCF) scattering. Particularly at lower temperature, PCF scattering plays a more significant role in the changing trend of the electron mobility.

In this paper, we investigate a nonlinear system, which describes the marginally unstable baroclinic wave packets in the geophysical fluid. Based on the symbolic computation and Hirota method, bright one- and two-soliton solutions for such a system are derived. Propagation and collisions of the solitons are graphically shown and discussed with $\beta$, which reflects the collision between the wave packet and mean flow, $\alpha$, which measures the state of the basic flow, and group velocity $\gamma$. $\gamma$ is observed to affect the amplitudes of the solitons, and $\alpha$ can influence the solitons’ traveling directions. By virtue of the generalized Darboux transformation, the first- and second-order rogue-wave solutions are derived. Properties of the first- and second-order rogue waves are graphically presented and analyzed: The first-order rogue waves are shown in the figures. $\alpha$ has no effects on A, which is the amplitude of the wave packet, but with the increase of $\alpha$, amplitude of B, which is a quantity measuring the correction of the basic flow, decreases. When $\beta$ is chosen differently, A and B do not keep their shapes invariant. With the value of $\gamma$ increasing, amplitudes of A and B become larger. The second-order rogue wave is presented, from which we observe that with $\alpha$ increasing, amplitude of B decreases, but $\alpha$ has no effects on A. Collision features of A and B alter with the value of $\beta$ changing. When we make the value of $\gamma$ larger, amplitudes of A and B increase.

The phase stability, mechanical properties and lattice thermal conductivity of the ternary layered ceramic Ti₂(Al${}_x$Sn${}_{1-x}$)C solid solutions are systematically investigated using the first-principles calculation. Present calculated results indicate that all the Ti₂(Al${}_x$Sn${}_{1-x}$)C solid solutions are thermodynamic and elastically stable and all these compounds are identified as brittle materials. The temperature dependence of lattice thermal conductivity and the minimum thermal conductivity of the Ti₂(Al${}_x$Sn${}_{1-x}$)C compounds are reported. Moreover, Debye temperature and melting point of these compounds are also obtained. Present results predict that all Ti₂(Al${}_x$Sn${}_{1-x}$)C compounds have a relative high melting point and Debye temperature, indicating that all Ti₂(Al${}_x$Sn${}_{1-x}$)C compounds possess a rather stiff lattice and good thermal conductivity.

The structural, elastic and thermodynamic properties of the A15 structure V₃Ir, V₃Pt and V₃Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V₃Ir, V₃Pt and V₃Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

Recently, a multiparty semiquantum secret sharing scheme based on rearranging orders of qubits was proposed by Gao et al. [Mod. Phys. Lett. B 30 (2016) 1650130]. In this paper, we show that in their scheme the last agent and other agents can illegally get the sender’s secret keys without being detected. Furthermore, an improved scheme is proposed to resist such attack.

We investigate the tunneling transport for electrons on the surface of a topological insulator (TI) through an electrostatic potential barrier. By using the Dirac equation with the continuity conditions for all segments of wave functions at the interfaces between regions inside and outside the barrier, we calculate analytically the transmission probability and conductance for the system. It is demonstrated that, the Klein paradox can also been observed in the system same as in graphene system. Interestingly, the conductance reaches the minimum value when the incident electron energy is equal to the barrier strength. Moreover, with increasing barrier width, the conductance turns up some tunneling oscillation peaks, and larger barrier strength can cause lower conductance, shorter period but larger oscillation amplitude. The oscillation amplitude decreases as the barrier width increases, which is similar as that of the system consisting of the compressive uniaxial strain applied on a TI, but somewhat different from that of graphene system where the oscillation amplitude is a constant. The findings here imply that an electrostatic barrier can greatly influence the electron tunneling transport of the system, and may provide a new way to realize directional filtering of electrons.