Anomalous behavior induced by water insertion in Molybdenum disulfide nanoflowers

The coexistence of negative photoconductivity and metallic-like behavior in conventional semiconductors is very uncommon. In this work, we report the existence of such unconventional physical properties in Molybdenum disulfide nanoflowers (MoS2-NF). This is achieved by making the surface of MoS2 hygroscopic by alcohol treatment and creating a transport channel that favors protonic over electronic conduction. On cooling the MoS2-NF in a heat sink, the excess water that condenses on the surface forms a proton (H3O+) wire which exhibits pinched hysteresis characteristics. The conductivity of MoS2 increased by two orders of magnitude in the proton-dominated conduction regime with an exceptionally high positive temperature coefficient of 1.3×104 Ω/K. Interestingly, MoS2-NF also exhibits strong negative photoresponse (NPC) at room temperature when illuminated with UV and infra-red radiation. This interesting behavior observed in MoS2 NF can be useful for energy harvesting applications and the realization of fast thermal memories and optical switches.

New Grounded and Floating Memristor-Less Meminductor Emulators Using VDTA and CDBA

In this paper, new memristor-less meminductor emulators have been proposed using voltage differencing transconductance amplifier (VDTA), current differencing buffered amplifier (CDBA) and a grounded capacitor. The proposed decremental/incremental meminductor emulators have been realized in both grounded and floating types of configurations. In the proposed meminductor emulators, analog multiplier, memristor and passive resistors are not used which result in simpler configurations. The pinched hysteresis loops are maintained up to 2[Formula: see text]MHz for both decremental and incremental configurations of meminductor emulators. The behaviors of decremental and incremental meminductor emulators have been analyzed after applying input pulses. The obtained results verify the performances as decremental and incremental meminductor emulators. The simulation results have been obtained using Mentor Graphics Eldo simulation tool with 180[Formula: see text]nm CMOS technology parameters. To verify the performances of the proposed meminductor emulators, adaptive learning circuit and chaotic oscillator have been designed. The performances of the proposed meminductor emulators are compared with other meminductor emulators reported in the literature.

A S-Type Bistable Locally-Active Memristor and Its Application in Oscillator Circuit

In this paper, a S-type memristor with tangent nonlinearity is proposed. The introduced memristor can generate two kinds of stable pinched hysteresis loops with initial conditions from two flanks of the initial critical point. The power-off plot verifies that the memristor is nonvolatile, and the DC V-I plot shows that the memristor is locally active with the locally-active region symmetrical about the origin. The equivalent circuit of the memristor, derived by small-signal analysis method, is used to study the dynamics near the operating point in the locally-active region. Owing to the bistable and locally-active properties and S-type DC V-I curve, this memristor is called S-type BLAM for short. Then, a new Wien-bridge oscillator circuit is designed by substituting one of its resistances with S-type BLAM. It find that the circuit system can produce chaotic oscillation and complex dynamic behavior, which is further confirmed by analog circuit experiment.

Novel Meminductor Emulators Using Operational Amplifiers and their Applications in Chaotic Oscillators

This paper presents six different meminductor emulator circuits based on operational amplifiers. Five circuits of meminductor emulators have been proposed using two operational amplifiers, one memristor, three resistors and one capacitor, whereas the sixth circuit uses two operational amplifiers, two memristors, one resistor and two capacitors. All circuits of the proposed meminductor emulators are very simple over most of the realizations of meminductor emulators in the literature. The behaviors of meminductor emulators are satisfactory over a wide range of frequencies. The proposed configurations of meminductor emulators have been simulated by the LTspice tool. The SPICE models of both operational amplifier (AD711) and memristor have been used for simulation. The workability of the proposed meminductor emulators has also been verified using the basic and well-known structure of operational amplifier. In addition, the pinched hysteresis loop obtained by the simulation results of meminductor emulator has been achieved by the experimental results as well. Chaotic oscillator has been designed using the proposed meminductor emulator to prove the worthiness of the design.

Second Generation Current Conveyor Based Floating Fractional Order Memristance Simulator and a New Dynamical System

In recent years, due to its non-volatile memory, non-locality, and weak singularity features, fractional calculations have begun to take place frequently in artificial neural network implementations and learning algorithms. Therefore, there is a need for circuit element implementations providing fractional function behaviors for the physical realization of these neural networks. In this study, a previously defined integer order memristor element equation is changed and a fractional order memristor is given in a similar structure. By using the obtained mathematical equation, frequency-dependent pinched hysteresis loops are obtained. A memristance simulator circuit that provides the proposed mathematical relationship is proposed. Spice simulations of the circuit are run and it is seen that they are in good agreement with the theory. Also, the non-volatility feature has been demonstrated with Spice simulations. The proposed circuit can be realized by using the integrated circuit elements available on the market. With a small connection change, the proposed structure can be used to produce both positive and negative memristance values.

Locally Active Memristor with Three Coexisting Pinched Hysteresis Loops and Its Emulator Circuit

Locally active memristors with multiple coexisting pinched hysteresis loops have attracted the attention of researchers. However, the currently reported multiple coexisting pinched hysteresis loops memristors are obtained by adding additional piecewise-linear terms into the original Chua corsage memristor. This paper proposes a novel locally active memristor by introducing a polynomial characteristic function into the state equation. The novel memristor has three coexisting pinched hysteresis loops, large relative range of active region and simple emulator circuit. The characteristics of the novel memristor such as power-off plot, coexisting pinched hysteresis loops and DC [Formula: see text]–[Formula: see text] plot are studied. The memristor is used in a Chua chaotic system to investigate the effects of locally active characteristic on the chaotic oscillation system. Furthermore, the memristor emulator and chaotic system are designed and implemented by commercial circuit elements. The hardware experiments are consistent with numerical simulations.

A Novel Bipolar Photon-Controlled Generalized Memristor Based on Avalanche Photodiode

A novel bipolar photon-controlled generalized memristor model with an avalanche photodiode (APD) passive quenching circuit is presented in this paper. The SPICE model of the circuit is established and its fingerprints are analyzed by the pinched hysteresis loops with different bipolar periodic stimuli. The dynamical characteristics of the proposed circuit model are investigated both theoretically and simulatively. The results verified by Cadence Spectre circuit simulator demonstrate that the proposed circuit model is a simple bipolar photon-controlled generalized memristor. Compared with the previously published memristor models, the biggest innovation of this paper is to propose a bipolar generalized memristor model instead of the traditional model, which can easily form the pinched hysteresis loop. Another highlight is that the generalized memristor model in this paper is controlled by photons while conventional memristors are charge-controlled/flux-controlled. Furthermore, the circuit level models are more stable, more reliable and more resistant to interference than the device level models. The topological structure of the proposed circuit model in this paper is much more simpler.