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This study investigated quantum tunneling of spin-half particles through the event horizon of a Rindler modified Schwarzschild black hole (RMSBH) in the presence of quintessence matter. We analyzed the thermodynamics of RMSBH in Kiselev coordinates. In particular, we explore the RMSBH's entropy and thermal stability. We showed that RMSBH serves as an unstable system, causing fluctuations. The integral formulation of the first law of RMSBH in the absence of a cosmological constant was also represented. By using the first law, we have studied the Ruppeiner geometry for Rindler acceleration and pressure with fixed ensembles. Key words: fermion tunneling, hawking temperature, thermodynamics fluctuation, microscopic structure, Rindler modified Schwarzschild black hole. Cette etude examine l'effet tunnel quantique de particules de spin 1/2 a travers l'horizon d'un trou noir de Schwarzschild modifie par Rindler (TNSMR/RMSBH) en presence de quintessence. Nous analysons la thermodynamique de ce trou noir dans les coordonnees de Kiselev. En particulier, nous explorons son entropie et sa stabilite thermique. Nous montrons que c'est un systeme instable causant des fluctuations. Nous presentons egalement la formulation integrale de la premiere loi pour ces trous noirs en l'absence de constante cosmologique. Finalement, en utilisant la premiere loi, nous etudions la geometrie de Ruppeiner pour l'acceleration et la pression de Rindler avec des ensembles fixes. [Traduit par la Redaction] Mots-cles : effet tunnel de fermions, temperature de Hawking, fluctuation thermodynamique, structure microscopique, trou noir de Schwarzschild modifie par Rindler., 1. Introduction Black holes (BHs) are very interesting objects in theoretical physics. The perception of their dynamics drives us to fit together two broadly accepted theories of nature: Einstein's theory [...]

Considering the modified Lorentz dispersion relation, combined with the Dirac equation and Rarita-Schwinger equation of fermions in stationary axisymmetric Sen black hole space-time, the fermion tunneling radiation of the black hole is modified accurately, and meaningful physical quantities such as the modified fermion tunneling rate, event horizon temperature, and entropy of the black hole are obtained. The discussion of the conclusions shows that the effect of the Lorentz dispersion relation and Lorentz violation theory on particle dynamics must be considered in curved space-time during the study of quantum theory and Hawking tunneling radiation. Key words: modification, Sen black hole, tunneling radiation, Hawking radiation, Lorentz invariance violation. Combinant la relation de dispersion de Lorentz modifiee avec les equations de Dirac et de Rarita-Schwinger pour des fermions dans un espace-temps de trou noir de Sen axisymetrique et stationnaire, nous obtenons le taux de radiation de fermions par effet tunnel, la temperature de l'horizon et l'entropie du trou noir. L'analyse des conclusions montre que les effets de la relation de dispersion de Lorentz et de la theorie de la violation de Lorentz sur la dynamique des particules, doivent etre pris en compte dans l'espace-temps courbe pendant l'etude des effets quantiques et de la radiation tunnel de Hawking. Mots-cles: modification, trou noir de Sen, radiation (par effet) tunnel, radiation de Hawking, violation de (l'invariance de) Lorentz., 1. Introduction The study of the theory of general relativity and quantum fields shows that the Lorentz relation can be modified in a high energy field and the magnitude of [...]

Tunnelling is one of the most characteristic phenomena of quantum physics, underlying processes such as photosynthesis and nuclear fusion, as well as devices ranging from superconducting quantum interference device (SQUID) magnetometers to superconducting qubits for quantum computers. The question of how long a particle takes to tunnel through a barrier, however, has remained contentious since the first attempts to calculate it.sup.1. It is now well understood that the group delay.sup.2--the arrival time of the peak of the transmitted wavepacket at the far side of the barrier--can be smaller than the barrier thickness divided by the speed of light, without violating causality. This has been confirmed by many experiments.sup.3-6, and a recent work even claims that tunnelling may take no time at all.sup.7. There have also been efforts to identify a different timescale that would better describe how long a given particle spends in the barrier region.sup.8-10. Here we directly measure such a time by studying Bose-condensed .sup.87Rb atoms tunnelling through a 1.3-micrometre-thick optical barrier. By localizing a pseudo-magnetic field inside the barrier, we use the spin precession of the atoms as a clock to measure the time that they require to cross the classically forbidden region. We study the dependence of the traversal time on the incident energy, finding a value of 0.61(7) milliseconds at the lowest energy for which tunnelling is observable. This experiment lays the groundwork for addressing fundamental questions about history in quantum mechanics: for instance, what we can learn about where a particle was at earlier times by observing where it is now.sup.11-13. Using the spin precession of Bose-condensed .sup.87Rb atoms as a clock, direct measurements are made of the time required for Rb atoms to quantum tunnel through a classically impenetrable barrier., Author(s): Ramón Ramos [sup.1] [sup.3] , David Spierings [sup.1] , Isabelle Racicot [sup.1] , Aephraim M. Steinberg [sup.1] [sup.2] Author Affiliations: (1) Centre for Quantum Information and Quantum Control and [...]

Taking into account quantum gravity effect influenced by the generalized uncertain principle (GUP), via modified Dirac equation, we discuss the quantum gravity correction to fermion tunneling and the remnant in a five-dimensional Myers-Perry black hole. By analyzing the modified tunneling probability, we find that the emission spectrum is no longer pure thermal. Furthermore, it is worth emphasizing that the quantum gravity correction influenced by GUP prevents the black hole from evaporating totally, resulting in a black hole remnant. Key words: generalized uncertain principle, modified Dirac equation, fermion tunneling, remnant, five dimensional Myers-Perry black hole. Prenant en compte l'effet de la gravite quantique influencee par un principe d'incertitude generalise (GPU/PIG), via une equation de Dirac modifiee, nous discutons la correction de la gravite quantique a l'effet tunnel de fermion et le vestige, dans trou noir de Myers-Perry en cinq dimensions. Analysant la probabilite d'effet tunnel modifie, nous trouvons que le spectre d'emission n'est plus purement thermique. De plus, il faut insister sur le fait que la gravite quantique influencee par GPU/PIG empeche le trou noir de s'evaporer completement, laissant un vestige de trou noir. [Traduit par la Redaction] Mots-cles: principe d'incertitude generalise, equation de Dirac modifie, effet tunnel de fermion, trou noir de Myers-Perry en cinq dimensions., 1. Introduction It is well known that Hawking radiation, originally discovered by Hawking [1], is one of the most surprising achievements. Generally speaking, there are two universal approaches used to [...]

The quantum condensate of Cooper pairs forming a superconductor was originally conceived as being translationally invariant. In theory, however, pairs can exist with finite momentum Q, thus generating a state [...]

In this study, the effects of annealing conditions on the magnetic characteristics of multilayered perpendicular magnetic tunnel junctions (pMTJ) of the structures SiNx/Pt/[(Co/Pd).sub.10]/MgO/[(Co/Pt).sub.5]/Pt with various MgO barrier thicknesses were explored. We found that both the fixed and free layers exhibit coercivity growth with increasing annealing temperature. Insertion of a 0.4 nm Mg layer under the MgO barrier layer increases the corecivities further. Magnetoresistance measured by the current-in-plane tunneling (CIPT) method reveals that the insertion of Mg layers on both side of the MgO layer can increase the MR ratio by up to 32%. Index Terms--Co/Pd, Co/Pt, MgO, perpendicular magnetic tunnel junction (pMTJ), tunneling magnetoresistance (TMR).

The small curvature method is used for calculating the variational transition-state theory constants with multidimensional tunneling contributions for the C[F.sub.3]C[H.sub.2]C[H.sub.3] + OH reaction. The reliability of the structure activity relationship that is used for estimating the rate constant values for OH reactions with hydrofluorocarbons is discussed.

The ultimate scaling limits of p-i-n carbon-nanotube field-effect transistors (CNT-FETs) are examined using numerical simulations that are based on a quantum-mechanical transport within the nonequilibrium Green's function formalism. The results have shown that there is no speed advantage in scaling the gate length of the p-i-n CNT-FETs below 16 nm because of the rapid increase of the tunneling current in the subthreshold region.

Ramped stress breakdown test was applied to estimate lifetime of tunneling magnetoresistance (TMR) heads for the intrinsic and extrinsic breakdown failure mode based on both E and 1/E models. The ramp voltage stress failure was transferred into the constant voltage stress prediction and closed form expressions of time-to-failure for both E and 1/E models were deduced. The parameters for these expressions were fitted by the experimental data at various ramp step times and the time-to-failure was calculated using these fitted parameters. The heads with larger breakdown voltage showed longer lifetime for the same ramp step time, and the shorter lifetime heads were from the lower magnetic reader resistance range. The thermal acceleration was too slow for TMR lifetime projection, and the lifetime showed bimodal distribution due to the extrinsic and intrinsic breakdown behaviors, the extrinsic breakdown heads showed shorter lifetime compared with the intrinsic breakdown heads. Index Terms--Dielectric breakdown, life estimation, reliability, tunneling.

The spin polarization and the corresponding tunneling magnetoresistance (TMR) for a hybrid ferromagnetic/superconductor junction are calculated. The results show that these parameters are strongly depends on the exchange field energy [...]

The one-band envelope function approximation if used for examining the spin-dependent tunneling of conduction band electrons in semiconductor heterostructures when both the bulk inversion asymmetry (BIA) and structure inversion asymmetry (SIA) are present. The interplay between BIA and SIA are used for inducing a strong dependence of transmission probabilities on the direction of electrons lateral momenta thus providing means to improve the existing designs of nonmagnetic semiconductor spin filters.

The dependence of the photon (H)-atom tunneling in Debye approximation of the expression of the rate constant on temperature and pressure is discussed. The oscillatory barrier preparation and media reorganization are the two mechanisms that affect the temperature dependence of this phenomenon.

Optical methods are used to investigate the effects of correlation in the quantum Hall (QH) regimes of electron double layers with finite tunneling at Landau level filling factor v=1. The correlated QH state has exhibited resonant Rayleigh scattering with uncommon temperature dependence.

The experiments and theoretical analyses of spin-charge separation and the spin-incoherent regime in low-density electron systems are presented. The results have shown that electron-electron interactions have strong effects on the low-energy excitations of the one-dimensional metal.

A highly tunable double dot-ring system is studied, where the Aharonov-Bohm (AB) effect is used to examine the phase coherent contributions to elastic and inelastic cotunneting currents. Pronounced AB oscillations in the ring with visibilities exceeding 80% are observed for the strong tunnel coupling and low bias.

This paper considers high-frequency (200 kHz-1.0 MHz) losses in MnZn power ferrites and shows that none of the three well-known magnetic loss mechanisms (namely, hysteresis, classical eddy-current loss, and excess eddy-current loss) can account for the experimentally observed dependence of the loss on the frequency and flux density. In order to investigate the origin of this discrepancy, the electric field that is induced in the typical core when the material is driven at high frequencies and flux densities was estimated. The estimates show that these electric fields can be quite large. The paper presents experimental data on the electrical conductivity for such large electric fields, which shows a highly nonlinear behavior that can give rise to a modified eddy-current loss mechanism. By a simple curve fit to the nonlinear conductivity, the experimentally observed flux density dependence of the high-frequency loss, which previously could not be explained, can be reproduced by using this modified eddy-current loss mechanism. A modified ferrite structure can eliminate most of these extra losses by reducing the electric field generated at the grain boundaries due to high frequencies and flux densities. Index Terms--Eddy currents, electric fields, ferrite devices, ferrites, ferromagnetic materials, granular materials, inductors, losses, magnetic losses, power conversion, power electronics, power transformers.

Tunneling magnetoresistive (TMR) heads have been observed to exhibit relatively large low-frequency noise. Observation in a saturating field reveals that a substantial part of this noise is of electrical origin. Two distinctly different electrical noise phenomena are observed: 1/f noise and random telegraph (RT) noise. 1/f noise appears in all heads, RT noise only in some. The magnitude of the noise tracks the device resistance and the electrical bias. Therefore, the question arises if it is caused by resistance fluctuations or by the electrical bias. To answer this question, the paper describes a measurement setup to determine the TMR device noise in thermodynamic equilibrium (no bias). It is concluded that at zero bias there is no electrical low-frequency noise; neither 1/f noise nor RT noise was detected. Further, the paper proposes an electroacoustic model for the origin of the 1/f noise and estimates the expected magnitude. For the RT noise, in addition to the well-known trapped charge blocking model, an electromigratory model is proposed to better cover all observed RT noise features. Index Terms--Low-frequency noise, noise modeling, 1/f noise, random telegraph noise, tunneling magnetoresistive noise

Use of the pressure dependence of kinetic isotope effects, coupled with a study of their temperature dependence, as a probe for promoting motions in enzymatic hydrogen-tunneling reactions is reported. Employing morphinone reductase as our model system and by using stopped-flow methods, we measured the hydride transfer rate (a tunneling reaction) as a function of hydrostatic pressure and temperature. Increasing the pressure from 1 bar (1 bar = 100 kPa) to 2 kbar accelerates the hydride transfer reaction when both protium (from 50 to 161 [s.sup.-1] at 25[degrees]C) and deuterium (12 to 31 [s.sup.-1] at 25[degrees]C) are transferred. We found that the observed primary kinetic isotope effect increases with pressure (from 4.0 to 5.2 at 25[degrees]C), an observation incompatible with the Bell correction model for hydrogen tunneling but consistent with a full tunneling model. By numerical modeling, we show that both the pressure and temperature dependencies of the reaction rates are consistent with the framework of the environmentally coupled tunneling model of Kuznetsov and Ulstrup [Kuznetsov AM, Ulstrup J (1999) Can J Chem 77:1085-1096], providing additional support for the role of a promoting motion in the hydride tunneling reaction in morphinone reductase. Our study demonstrates the utility of 'barrier engineering' by using hydrostatic pressure as a probe for tunneling regimes in enzyme systems and provides added and independent support for the requirement of promoting motions in such tunneling reactions. flavoprotein | hydrogen tunneling | morphinone reductase | pressure dependence | stopped flow

Ab initio electronic structure theory calculations on model systems are used for the comparison of tunneling through covalently bonded contacts, hydrogen bonds, and van der Waals contacts. The results have shown that a modest difference is observed between tunneling mediated by H-bonds and tunneling mediated by van der Waals contacts at typical distances for each type of interaction.

Two distinct monolayers are placed side by side using scanning probe nanolithography and the tunneling currents are compared by conductive probe atomic force microscopy under identical force for measuring relatively small differences in electron tunneling. The relative values of the two tunneling currents, calculated using density functional theory and the Tersoff-Hamann approach compare very well with the experimental data.

Electrostatic discharge (ESD) reliability simulations at circuit-level are used to develop an approach for modeling the breakdown and snapback behavior of advanced MOSFET structures. The junction and gate leakage currents due to increased tunneling in the scaled-down CMOS technologies are described, and parameter extraction procedures for the model parameters are also presented.

The well-defined one-electron steps in the voltammetry of solutions of the nanoparticles Au38(SC2Ph)24 and Au140(SC6)53 enable preparation of solutions containing for example Au38(SC2Ph)24 and Au 38(SC2Ph)24 [[.sup.(CIO4)].sup.-] nanoparticles in known relative proportions. Differences in pre-exponential terms in the activation equations for the two nanoparticles are a smaller contributor to the rate constant difference and could be partly ascribed to differences in tunneling distances.

Temperature-dependent subthreshold and gate-oxide leakage power characteristics of domino logic circuits under the influence of process parameter variations are evaluated in this paper. Preferred input vectors and node voltage states that minimize the total leakage power consumption are identified at the lower and upper extremes of a typical die temperature spectrum. New low-leakage circuit design guidelines are presented based on the results. Significantly increased gate dielectric tunneling current, as described in this paper, dramatically changes the leakage power characteristics of dynamic circuits in deeply scaled nanometer CMOS technologies. Contrary to the previously published techniques, a charged dynamic-node voltage state with low inputs is preferred for reducing the total leakage power consumption in the most widely used types of single- and dual-threshold voltage domino gates, particularly at low die temperatures. Furthermore, leakage power savings provided by the dual-threshold voltage domino logic circuit techniques based on input gating are all together reduced due to the significance of gate dielectric tunneling in sub-45-nm CMOS technologies. Index Terms--Domino logic, dual-[V.sub.t], dynamic circuits, gate-oxide leakage, subthreshold leakage.

Abstract: Scalar field theory with an asymmetric potential was studied at zero temperature and high-temperature for [[PHI].sup.6] potential. The equations of motion are solved numerically to obtain O(4) spherical symmetric [...]

Abstract: We summarize our study of a diatomic homonuclear molecule incident upon a potential barrier in one dimension [G.L. Goodvin and M.R.A. Shegelski. Phys. Rev. A, 71, 032719 (2005).]. We [...]

An increasingly comprehensive body of literature is being devoted to single-molecule bridge-mediated electronic nanojunctions, prompted by their prospective applications in molecular electronics and single-molecule analysis. These junctions may operate in gas phase or electrolyte solution (in situ). For biomolecules, the latter is much closer to their native environment. Convenient target molecules are aromatic molecules, peptides, oligonucleotides, transition metal complexes, and, broadly, molecules with repetitive units, for which the conducting orbitals are energetically well below electronic levels of the solvent. A key feature for these junctions is rectification in the current-voltage relation. A common view is that asymmetric molecules or asymmetric links to the electrodes are needed to acquire rectification. However, as we show here, this requirement could be different in situ, where a structurally symmetric system can provide rectification because of the Debye screening of the electric field in the nanogap if the screening length is smaller than the bridge length. The Galvani potentials of each electrode can be varied independently and lead to a transistor effect. We explore this behavior for the superexchange mechanism of electron transport, appropriate for a wide class of molecules. We also include the effect of conformational fluctuations on the lowest unoccupied molecular orbital (LUMO) energy levels; that gives rise to non-Arrhenius temperature dependence of the conductance, affected by the molecule length. Our study offers an analytical formula for the current-voltage characteristics that demonstrates all these features. A detailed physical interpretation of the results is given with a discussion of reported experimental data. tunneling junction | molecular rectifier

The unimolecular dissociation of isopropyl chloride cation using mass- analyzed ion kinetic energy spectrometry is investigated. The dissociation mechanism for the loss of hydrogen chloride (HCL) from isopropyl chloride cation is described.

Experimental data and analysis show that overerase effects in NOR Flash memories increase with the electric field used during erasing. It is shown that cell degradation during erasing has to be ascribed to hole injection rather than to electron injection and that both hole trapping and detrapping increase with the electric field.

The time-dependent characteristics of quantum mechanical tunneling, fast tunneling in the early stage and slow and long-lasting tunneling in the later stage are studied. The results show that slow tunneling in the long time region is important, because it should dominate the time-dependent feature of tunneling.

The tunneling current for electrons tunneling between crystalline ferromagnetic electrodes through an epitaxial crystalline barrier can be calculated from first principles. These calculations show that the wave function symmetry can be exploited to achieve very high tunneling magnetoresistance. For the Fe(100)[MgO(100) [Fe(100) system, the calculated conductance is much higher and its decrease with MgO thickness is much slower than has been estimated using a simple free electron-barrier model. Index Terms--Co, cobalt, Fe, iron, magnesium oxide, magnetoresistance, MgO, symmetry, tunneling.

A quantum-mechanical transmission problem for the metal-oxide-semiconductor (MOS) capacitor with open boundaries is formulated by considering a MOS capacitor and a metallic lead attached to them as a closed system. The computation of the leakage current though an ultrathin gate oxide according to the obtained analytical expressions agrees well with the experimental data without the use of fitting parameters.

Spin-dependent tunneling in semiconductor symmetric double barrier structures is analyzed with calculations based on the effective one-band Hamiltonian and Dresslhaus spin-orbit coupling. The results demonstrate that the ratio of the tunneling times of electrons with opposite spin orientations can vary over a few orders in magnitude.

A study is carried out on the oscillation of the direct tunneling current through the oxide of a metal-oxide-semiconductor (MOS) capacitor at high-applied gate voltages. The tunneling current based on pure quantum-mechanical assumptions is calculated, resulting in oscillations at high electric fields imposed on the monotonically increasing current.

Modulation technique is used to detect a short-range interaction between a probe and a sample of a tunneling near-field optical microscope. It was observed that the effect of the coupled dipoles interaction is negligible in conventional near-field microscopes and it dominates the modulated signal at scanning distances.

Reaction rates extracted from measurements of donor luminescence quenching by randomly dispersed electron acceptors reveal an exponential decay constant of 1.23 per angstrom for electron tunneling through a frozen toluene glass (with a barrier to tunneling of 1.4 electron volts). The decay constant is 1.62 per angstrom (the barrier, 2.6 electron volts) in a frozen 2-methyl-tetrahydrofuran glass. Comparison to decay constants for tunneling across covalently linked xylyl (0.76 per angstrom) and alkyl (1.0 per angstrom) bridges leads to the conclusion that tunneling between solvent molecules separated by ~2 angstroms (van der Waals contact) is 20 to 50 times slower than tunneling through a comparable length of a covalently bonded bridge. Our results provide experimental confirmation that covalently bonded pathways can facilitate electron flow through folded polypeptide structures., Electron tunneling processes have been found to play pivotal roles in solid-state physics (1), chemistry (2), and biology (3, 4). In molecular systems, electron tunneling is commonly described in terms [...]

A study is carried out on the transition between off-resonance and on-resonance scattering states with the same incident energy, in response to a sudden change in the well depth of a double barrier potential structure. The studies show that for a larger change in the well depth beyond a critical depth, trapping dominates rather than decay, as the resonance becomes a bound state.

Thermotunnel effects are evaluated in ambient thermal energy scavenging configuration. A controlled realization process, which could allow thermotunnelling devices to be integrated in a small sensor node, still requires time and further technological developments.

Theoretical analysis of nonadiabatic electron-transfer reactions in molecules usually assumes that electron amplitude propogates coherently from the reductant to the oxidant via covalent and noncovalent coupling pathways. An attempt is made to show that when the tunneling electron excites local bridge vibrations (inelastic tunneling), the excitation 'labels' the physical pathway traversed.

The concept of time-dependent overlap between Wannier functions is introduced. The proposed tome-dependent overlap coefficient and results obtained could aid in the study and design of new electronic devices.

The study demonstrates the ZINDO model as accurate and efficient when employed for tunneling currents, calculations and can be utilized in studies of electron tunneling in large biological systems. The advantage of this model is that it employs STO basis functions, which decays more slowly than GTO functions, so the weak tunneling interactions of noncovalently bonded atoms of the protein can be accounted for minimum basis set.

Fabrication of superconductor-insulator-superconductor (SIS) mixers with Nb/Al-AIN/Nb tunnel junctions is described.

Properties of thermally grown aluminum oxide tunnel barriers are investigated and reported.

Insertion of a thin nonmagnetic copper Cu(001) layer between the tunnel barrier and the ferromagnetic electrode of a magnetic tunnel junction is shown to result in the oscillation of the tunnel magnetoresistance as a function of the Cu layer thickness. The effect is interpreted in terms of the formation of spin-polarized resonant tunneling. The amplitude of the oscillation is so large that even the sign of the tunnel magnetoresistance alternates. The oscillation period depends on the applied bias voltage, reflecting the energy band structure of Cu. The results are encouraging for the development of spin-dependent resonant tunneling devices., A new field of electronics called spin electronics (1, 2), which makes use of both the electric charge and the spin of conduction electrons, has been developing rapidly in systems [...]

A new algorithm is presented for carrying out large-curvature tunneling (LCT) calculations. It is tested on five hydrogen-atom transfer reactions and it is found that more than an order of magnitude can reduce the cost of LCT calculations.

Research has been conducted on the hydrogen quantum mechanical tunneling. The role of this tunneling in the hydrogen-transfer reactions and the effect of complex kinetics on the Swain-Schaad relationship have been investigated and the details are presented.