International Journal of Modern Physics B

This paper addresses the effect of temperature variation on the performance of a novel device structure Si-doped Hf$O_2$ negative capacitance junctionless tunnel field effect transistor (Si:Hf$O_2$ NC-JLTFET). Here, Si:Hf$O_2$ ferroelectric material is deployed as gate stack along with high-K gate dielectric Hf$O_2$. Si:Hf$O_2$ ferroelectric material generates NC effect during the device operation. This phenomenon is an effective technique for intrinsic voltage amplification, reduction in power supply, as well as minimization of power dissipation. The proposed device structure has two variants, symmetric and asymmetric with respect to the oxide thickness between electrode and Si body at both drain and source sides. As band-to-band tunneling in TFET is temperature dependent, it is very crucial to analyze the impact of temperature variation on the device performance. This work is mainly focused on investigating the device dc performance parameters, analog/RF performance parameters and linearity performance parameters by observing the impact of temperature variation. The device characteristics reveal that for dc and RF performance parameters, asymmetric structure shows better result. Highest $I_{\mathrm{\text{ON}}}/I_{\mathrm{\text{OFF}}}$ ratio and minimum SS are reported as $1.63\times 10^{12}$ and 20.038 mV/dec, respectively, at 300K for asymmetric structure. At elevated temperatures higher cutoff frequency and reduced intrinsic delay project the device as a strong candidate for ultra low-power and high switching speed applications. Further, the reported device shows better linearity performance at higher temperatures.

Ni–Al₂O₃ composite coatings were prepared with a modified Watt’s bath by using jet electrodeposition method. As the key process parameter, current density and the addition of Al₂O₃ nanoparticles in electrolyte were studied about the effect on the surface morphology and co-deposition of Al₂O₃ nanoparticles of composite coating. The mechanical and tribological properties of the composite coating were also tested. The results show that properly increasing the current density and Al₂O₃ addition can increase the co-deposition of nanoparticles in the coating and promote the formation of a dense and refined coating structure. Using the optimized process parameters of current density (300 A/dm²) and Al₂O₃ addition (30 g/L), the co-deposition of Al₂O₃ in the composite coating can reach a maximum of 13.1 at.%. The hardness of the coating reaches the peak at 623 HV. The wear rate of the composite coating is also greatly reduced with optimized parameters.

Chaotic systems can be used for secure communication and image encryption by applying a variety of encryption algorithms. While most of the low-dimensional chaotic systems and maps can be estimated by using phase reconstruction and thus the safety in signal processing and propagation is attacked. In this paper, an initial-dependent dynamical system, which is developed from the Rössler system by adding memristive function and disturbance function on the memristive variable $z$, is presented for realizing image encryption and bifurcation analysis is supplied in detail. Time-varying disturbance from sampled variables is applied to control the memristive variable and the dependence of mode oscillation on initial values is enhanced. As a result, the dynamics of this memristive system is switched between different oscillation modes (e.g., periodical to chaotic, chaotic to chaotic) by activating the initial value, memristive gain and disturbance gain, respectively. From a dynamical viewpoint, the involvement of stochastic adjustment on the memristive variable can reset the initial value and then induce time-varying parameter regulation or switch on certain parameter embedded in the memristive nonlinearity and function, and thus the dynamics dependence on the initial setting is enhanced. Standard bifurcation analysis is carried out on this memristive system and then the sampled time series are used for image encryption, furthermore, the reliability for this scheme is discussed and suggestions for further study are supplied in the end.

Due to the universality of asymmetric coupling-excitation in neuronal system and the important role of firing pattern in neural information coding and transmission, synchronous target mode decision mechanism of electrically coupled neuron system under asymmetric excitation is studied in this paper. In the beginning, based on an asymmetric excitation system with symmetrical coupling, according to the phenomenon that Interval Spike Intervals Sequence (ISI) can coincide with the ISIs of a single neuron stimulated by a certain current, the concept of ‘virtual equivalent symmetrical stimulus current’ is put forward. Furthermore, it is also found that there is no relationship between the steady-state synchronous target mode and the coupling strength of symmetric coupled system under this situation. However, the following experiments of asymmetric coupling-excitation system show that there is a strong internal relationship between the almost complete synchronous stable firing mode and coupling strength as well as exciting currents. According to the experimental conclusion, a qualitative criterion is proposed, and then, on the basis that the system can be fully synchronized, the decision-making quantitative basis of the steady-state synchronization target mode of the given system is derived strictly. This study has important reference value for understanding the working state transition of neuronal system.

The nuclear transmutation in the nanosilicon under the influence of epithermal neutrons and the formation processes of charge carriers under the influence of gamma and beta rays emitted by unstable nuclei were theoretically and experimentally investigated. These studies may provide information on the origin and number of electroactive defects in neutron-irradiated nanosilicon.

The novel coupling Benjamin–Ono system is obtained with the dark parameterization approach.By solving these coupling equations, three typical explicit solutions including the traveling wave solution are constructed through the special property of the anyon-$n$ algebra. Several novel types of localized excitations are depicted with some solutions.

Cellulose nanofluids have a great application potential in the energy industry, and their thermal properties are substantially affected by the components and microstructures of nanofluids. Therefore, this study investigated the isobaric heat capacity and thermal conductivity of cellulose I$\beta$ nanofluids mixing with H₂O by molecular dynamics (MD). The results showed that the existence of water in cellulose increased the isobaric heat capacity of the system, especially for the random cellulose/H₂O nanofluids. Additionally, nonequilibrium molecular dynamics (NEMD) simulations based on the Fourier law of thermal conduction were conducted to examine the thermal conductivity of the simulated systems. As indicated by our results, the cellulose I$\beta$ crystal was advantageous in terms of its high directional thermal conductivity along the chain direction. Thus, the thermal conductivity of the cellulose/H₂O nanofluids along the chain direction used the high directional thermal conductivity of the cellulose I$\beta$ crystal. Consequently, the cellulose/H₂O nanofluids integrated the superiorities of high isobaric heat capacity of water and great directional thermal conductivity of cellulose I$\beta$ crystal, thereby improving the heat transfer efficiency in thermodynamic systems. In addition, the potential energy of the cellulose crystal system was mainly generated by intermolecular repulsion, while those of the cellulose/H₂O nanofluid systems were mainly produced through intermolecular attraction.

We calculate exponential growth constants $\varphi$ and $\sigma$ describing the asymptotic behavior of spanning forests and connected spanning subgraphs on strip graphs, with arbitrarily great length, of several two-dimensional lattices, including square, triangular, honeycomb, and certain heteropolygonal Archimedean lattices. By studying the limiting values as the strip widths get large, we infer lower and upper bounds on these exponential growth constants for the respective infinite lattices. Since our lower and upper bounds are quite close to each other, we can infer very accurate approximate values for these exponential growth constants, with fractional uncertainties ranging from $O(10^{-4})$ to $O(10^{-2})$. We show that $\varphi$ and $\sigma$ are monotonically increasing functions of vertex degree for these lattices.

The results of the investigation of two-layer Fe/Cr systems using the magneto-optical Kerr effect (MOKE) are presented in this paper. The samples were obtained by thermal evaporation in a vacuum with a thickness of individual layers from 2 nm to 50 nm. It was found that the presence of the Cr layer significantly affects the values of the coercivity and the Kerr angle. At a substrate temperature of 450 K, the value of the coercivity is almost half that of the same sample obtained at room temperature of the substrate. In addition, the influence of the order of deposition of layers, as well as the effect of a thin gold protective layer on the parameters measured by the Kerr method, is shown. These studies have shown that the MOKE can be used as an additional method for studying the composition of multilayer systems, granular alloys and spin-valve systems, using specific software methods.

Background: This paper is concerned with a nonlinear semi-continuum model for an ultrathin structure. The basic equations of the theoretical model for silicon micro/nanosheets are derived, and the geometric nonlinearity is introduced in the model. Methods: From two different approaches including the new strain energy and the new external potential energy, we establish the nonlinear semi-continuum theoretical model of silicon micro/nanosheets, respectively. A new dimensionless nonlinear semi-continuum parameter is defined. Based on the theoretical model, the characteristics of bending deformation and free vibration are revealed. Results: The relationships between bending deflection and atomic layers in thickness direction as well as the relaxation coefficient between atomic layers are analyzed. The resonance frequencies of free vibration and their relationship with atomic layers are calculated. By introducing the specific property parameters of silicon micro/nanomaterials, several numerical calculations have been carried out. Conclusion: The theoretical results are compared with other studies in the literature, such as nonlinear finite element method (FEM), experimental and classical results, to validate the semi-continuum model established in the present research. This work can provide new ideas for the mechanical analyses of micro/nanomaterials and structures, and the results could be foundations for the design and application of silicon micro/nanosheets.

Many practice problems can be transformed into complex networks, and complex network community discovery has become a hot research topic in various fields. The classic label propagation algorithm (LPA) can give community partition very quickly, but stability of the algorithm is poor due to random label propagation. To solve this problem, community leader principle is built and transition probability is introduced, a label propagation algorithm based on community leader and transition probability (CTLPA) is proposed. CTLPA selects threatened leaders and their communities according to the community leader principle, and uses the transition probability and the degree of the leader to jointly control the order for community merger, so that the threatened leader continuously devours the communities that threaten him, until a preliminary community partition is formed. To further reduce the number of community, in CTLPA, based on the characteristic of the community structure: close relationship within the community and sparse relationship outside the community, the closest communities are merged, until the final community partition is obtained. The CTLPA is compared with other five classic algorithms on LFR artificially generated networks and several real data sets. The experimental results show that CTLPA is robust in community partition, it always gives the same community partition, while the LPA will give different results from multiple independent runs. The number of community partition and the normalized mutual information (NMI) of the CTLPA are the best in most cases.

We consider a double-layer system made of two parallel bilayer graphene sheets separated by a dielectric medium. We calculate the finite-temperature electrical conductivity of the first layer due to charged impurities located in two layers. We study the effects of temperature, interlayer distance, dielectric constants and impurity concentration, carrier concentration on the electrical conductivity. We show the importance of charged impurities located in layer II in determining electrical conductivity of the first layer for small interlayer distance. The results in this paper give us more understanding about the long-range charged impurity scattering in bilayer graphene under the effect of the second one.

Dynamical behavior of the optical traveling pulses for the resonant nonlinear Schrödinger (RNS) equation with external periodic force is studied. Using a complex transformation we obtain an unperturbed dynamical system for the RNS equation. Existence of periodic optical pulses, solitary optical pulses of dark and bright types, breaking optical pulses is dispensed using phase plane analysis of the unperturbed dynamical system. Introducing an external perturbation to the unperturbed dynamical system, quasiperiodicity and chaotic features of the nonlinear optical pulses for the perturbed dynamical system are studied by varying the resonance parameter (c) with special values of other system parameters through different computational tools, like time series plot, phase plot, sensitivity plot, Lyapunov exponent, and Poincare section. The resonance parameter (c) acts as a control parameter on qualitative transition of the nonlinear optical pulses for the perturbed dynamical system from quasiperiodic motion to chaotic motion.