An ultralow power 3-terminal memory device with write capability in the off-state

In this work, we demonstrated a room temperature fabricated ZnO/Ta 2 O 5 transistor for low power compute-in-memory application. By writing during the off-state, the device programmed for compute-in-memory shows power consumption in nW. By using variable pulse amplitudes for SET/RESET allows control of the on/off ratio of resistance states without affecting power consumption. Benchmarked against other ReRAMs the device shows a competitive 8 nJ per transition, which allows a reduction of power consumption in comparison to a filamentary device

Necessary conditions for steep switching in a constant Resistor-Capacitor RCFET

We establish that the phenomenon of transient negative capacitance, conventionally linked to the delay in the response of a domain switching, of a ferroelectric material, and modelled by a non-linear capacitor, can in fact be considered to be more generally applicable to any phenomenon that can be represented by an RC-equivalent circuit. We demonstrate the conditions for sub-60 mV/dec switching in an RC-FET, even if the R and C were constant along both forward and backward sweeps. For semiconductor charge Qch, we show that the necessary condition for sub-60 mV/dec switching (dQch)/(dΨs) = (q/(kBT))Qch, where Ψs is the surface potential, is possible only if Qch > 0 (i.e. when the transistor is ON) during the backward sweep. This insight contributes further understanding on the causes of hysteresis in commonly used SPICE models of FE-FETs

Can We Improve the Preprocessing of Photospheric Vector Magnetograms by the Inclusion of Chromospheric Observations?

The solar magnetic field is key to understanding the physical processes in the solar atmosphere. Nonlinear force-free codes have been shown to be useful in extrapolating the coronal field upward from underlying vector boundary data. However, we can only measure the magnetic field vector routinely with high accuracy in the photosphere, and unfortunately these data do not fulfill the force-free condition. We must therefore apply some transformations to these data before nonlinear force-free extrapolation codes can be self-consistently applied. To this end, we have developed a minimization procedure that yields a more chromosphere-like field, using the measured photospheric field vectors as input. The procedure includes force-free consistency integrals, spatial smoothing, and -- newly included in the version presented here -- an improved match to the field direction as inferred from fibrils as can be observed in, e.g., chromospheric H$\alpha$ images. We test the procedure using a model active-region field that included buoyancy forces at the photospheric level. The proposed preprocessing method allows us to approximate the chromospheric vector field to within a few degrees and the free energy in the coronal field to within one percent.Comment: 22 pages, 6 Figur

Negative Capacitance beyond Ferroelectric Switches

Negative capacitance transistors are a unique class of switches capable of operation beyond the Boltzmann limit to realize subthermionic switching. To date, the negative capacitance effect has been predominantly attributed to devices employing an unstable insulator with ferroelectric properties, exhibiting a two-well energy landscape, in accordance with the Landau theory. The theory and operation of a solid electrolyte field effect transistor (SE-FET) of subthreshold swing less than 60 mV/dec in the absence of a ferroelectric gate dielectric are demonstrated in this work. Unlike ferroelectric FETs that rely on a sudden switching of dipoles to achieve negative capacitance, we demonstrate a distinctive mechanism that relies on the accumulation and dispersion of ions at the interfaces of the oxide, leading to a subthreshold slope (SS) as low as 26 mV/dec in these samples. The frequency of operation of these unscaled devices lies in a few millihertz because at higher or lower frequencies, the ions in the insulator are either too fast or too slow to produce voltage amplification. This is unlike Landau switches, where the SS remains below 60 mV/dec even under quasi-static sweep of the gate bias. The proposed FETs show a higher on-current with a thicker oxide in the entire range of gate voltage, clearly distinguishing their scaling laws from those of ferroelectric FETs. Our theory, validated with experiment, demonstrates a new class of devices capable of negative capacitance that opens up alternate methods of steep switching beyond the traditional approach of ferroelectric or memristive FETs

Hopping motion of lattice gases through nonsymmetric potentials under strong bias conditions

The hopping motion of lattice gases through potentials without mirror-reflection symmetry is investigated under various bias conditions. The model of 2 particles on a ring with 4 sites is solved explicitly; the resulting current in a sawtooth potential is discussed. The current of lattice gases in extended systems consisting of periodic repetitions of segments with sawtooth potentials is studied for different concentrations and values of the bias. Rectification effects are observed, similar to the single-particle case. A mean-field approximation for the current in the case of strong bias acting against the highest barriers in the system is made and compared with numerical simulations. The particle-vacancy symmetry of the model is discussed.Comment: 8 pages (incl. 6 eps figures); RevTeX 3.

Diffusion-Controlled Faradaic Charge Storage in High-Performance Solid Electrolyte-Gated Zinc Oxide Thin-Film Transistors

An electrochemical device capable of manifesting reversible charge storage at the interface of an active layer offers formidable advantages, such as low switching energy and long retention time, in realizing synaptic behavior for ultralow power neuromorphic systems. Contrary to a supercapacitor-based field-effect device that is prone to low memory retention due to fast discharge, a solid electrolyte-gated ZnO thin-film device exhibiting a battery-controlled charge storage mechanism via mobile charges at its interface with tantalum oxide is demonstrated. Analysis via cyclic voltammetry and chronoamperometry uniquely distinguishes the battery behavior of these devices, with an electromotive force generated due to polarization of charges strongly dependent on the scan rate of the applied voltage. The Faradaic-type diffusion-controlled charge storage mechanism exhibited by these devices is capable of delivering robust enhancement in the channel conductance and leads to a superior ON-OFF ratio of 108-109. The nonvolatile behavior of the interface charge storage and slow diffusion of ions is utilized in efficiently emulating spike timing-dependent plasticity (STDP) at similar time scales of biological synapses and unveils the possibility of STDP behavior using multiple in-plane gates that alleviate additional requirement of waveform-shaping circuits

Mechanistic basis of silicon mediated cold stress tolerance in alfalfa (Medicago sativa L.)

Cold stress (CS) impact on crops is one of the critical constraints for sustainable and smart agricultural production. CS adversely affects plants leading to growth retardation, necrosis, chlorosis, and significant yield loss. The objective of this study was to explore the mechanistic basis of silicon (Si) in enhancing CS tolerance in alfalfa plants. The fluorescence staining indicated that Si-reduced the intensity of CS-induced superoxide radical (O) and hydrogen peroxide (HO) generation in plants that improved plant photosynthesis, cellular integrity, and alfalfa biomass production under CS. The exogenous supplementation of Si significantly restored the endogenous Si status accompanied by the upregulation of NIP (nodulin 26-like intrinsic protein) genes NIP2, NIP5;1, and NIP6;1 in alfalfa. The elemental concentration analysis revealed that exogenous silicon (E-Si) triggers the increase of calcium (Ca), magnesium (Mg), and sulfur (S) in plants subjected to Si-supplementation compared to the plants cultivated without Si under CS. The application of Si significantly increased the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). Furthermore, Si significantly enhanced the expression of CS-responsive candidate genes including ICE1, CBF1/DREB1C, CBF2/DREB1B, CBF3/DREB1A, COR15A, COR47, and KIN1 in alfalfa. These findings together provide mechanistic insights into Si-involving CS tolerance in alfalfa. This eco-friendly SC management strategy using Si treatment can be useful to plant breeders and farmers for developing CS-resilient smart alfalfa production through breeding program.This study was supported by the RDA Fellowship Program of National Institute of Animal Science, and Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ01592501), Rural Development Administration, Republic of Kore

Influence of shower fluctuations and primary composition on studies of the shower longitudinal development

We study the influence of shower fluctuations, and the possible presence of different nuclear species in the primary cosmic ray spectrum, on the experimental determination of both shower energy and the proton air inelastic cross section from studies of the longitudinal development of atmospheric showers in fluorescence experiments. We investigate the potential of track length integral and shower size at maximum as estimators of shower energy. We find that at very high energy (~10^19-10^20 eV) the error of the total energy assignment is dominated by the dependence on the hadronic interaction model, and is of the order of 5%. At lower energy (~10^17-10^18 eV), the uncertainty of the energy determination due to the limited knowledge of the primary cosmic ray composition is more important. The distribution of depth of shower maximum is discussed as a measure of the proton-air cross section. Uncertainties in a possible experimental measurement of this cross section introduced by intrinsic shower fluctuations, the model of hadronic interactions, and the unknown mixture of primary nuclei in the cosmic radiation are numerically evaluated.Comment: 12 pages, 11 figures, 4 table

Schroedinger cat-like states by conditional measurements on a beam-splitter

A scheme for generating Schr\"{o}dinger cat-like states of a single-mode optical field by means of conditional measurement is proposed. Feeding into a beam splitter a squeezed vacuum and counting the photons in one of the output channels, the conditional states in the other output channel exhibit a number of properties that are very similar to those of superpositions of two coherent states with opposite phases. We present analytical and numerical results for the photon-number and quadrature-component distributions of the conditional states and their Wigner and Husimi functions. Further, we discuss the effect of realistic photocounting on the states.Comment: 6 figures(divided in subfigures) using a4.st

CP Phases in Correlated Production and Decay of Neutralinos in the Minimal Supersymmetric Standard Model

We investigate the associated production of neutralinos $e^+e^-\to\tilde{\chi}^0_1\tilde{\chi}^0_2$ accompanied by the neutralino leptonic decay $\tilde{\chi}^0_2\to\tilde{\chi}^0_1 \ell^+\ell^-$, taking into account initial beam polarization and production-decay spin correlations in the minimal supersymmetric standard model with general CP phases but without generational mixing in the slepton sector. The stringent constraints from the electron EDM on the CP phases are also included in the discussion. Initial beam polarizations lead to three CP--even distributions and one CP--odd distribution, which can be studied independently of the details of the neutralino decays. We find that the production cross section and the branching fractions of the leptonic neutralino decays are very sensitive to the CP phases. In addition, the production--decay spin correlations lead to several CP--even observables such as lepton invariant mass distribution, and lepton angular distribution, and one interesting T--odd (CP--odd) triple product of the initial electron momentum and two final lepton momenta, the size of which might be large enough to be measured at the high--luminosity future electron--positron collider or can play a complementary role in constraining the CP phases with the EDM constraints.Comment: Revtex, 37 pages, 12 eps figure