Ballistic transport under quantum Hall effect conditions

The paper addresses details of the single-particle electron spectrum ?_l(p)${?}_l(p)$ in narrow Coulomb channels (l is the transverse spectrum part discrete index and p   is the continuous longitudinal electron momentum). The channel is said to be narrow if differences between transverse spectrum branches ?_l(p)${?}_l(p)$ are larger than temperature. Considered are two extreme cases with respect to magnetic field. For the first case where ?_F≥?ω_c${?}_F\ge \mathit{?}{\omega }_c$, the spectrum ?_l(p)${?}_l(p)$ first calculated by Stern et al. numerically is obtained with approximate analytical analysis (here ?_F${?}_F$ is the Fermi energy of the 2D electron system ?ω_c$\mathit{?}{\omega }_c$ is the cyclotron frequency). In the second case the proposed formalism is extended to high magnetic fields satisfying the inequality ?_F≤?ω_c${?}_F\le \mathit{?}{\omega }_c$. Calculated results are compared with available experimental data.     

Shot noise in the hybrid triple-quantum-dot interferometer coupled to superconductor and normal terminals

The shot noise of a hybrid triple-quantum-dot (TQD) interferometer has been investigated by employing the nonequilibrium Green's function method, and the general shot noise formula has been derived. The oscillation behaviors of transmission coefficients and shot noise versus the Aharonov–Bohm phase ?   exhibit asymmetric Fano resonance structure and blockade effect. Sub-Poissonian and super-Poissonian behaviors of shot noise appear in different regimes of terminal bias e_Vγ$e{V}_{\gamma }$ contributed by the Andreev reflection, and correlation of Andreev tunneling with the normal electron transport. The inverse resonance and resonance structures emerge in the shot noise and Fano factor with respect to one of the gate voltages in different regimes of e_Vγ$e{V}_{\gamma }$. The asymmetric structure can be enhanced by modifying the energy levels and gate biases of the TQD. The self-correlation and cross-correlation of current components contribute to the enhancement and suppression of shot noise.     

Landau damping of dust acoustic waves in the plasma with nonextensive distribution

The Landau damping of dust acoustic waves propagating in a dusty plasma composed of nonextensive distributed electrons and ions, and Maxwellian distributed dust grains is investigated based on kinetic theory. The dust acoustic waves are found in the range of k_vd?ω?k_vi?k_ve$k{v}_d?\omega ?k{v}_i?k{v}_e$, where _vα$v_{\alpha }$ is the thermal velocity of species α(=i,e,d)$\alpha (=i,e,d)$. The damping rate is shown to be dependent on the nonextensivity parameter q$q$ as well as the ratio of ion density to electron. In the limit q→1$q\to 1$, the result based on the Maxwellian distribution is recovered. The maximum Landau damping rate is found to be enhanced as the population of the electron density decreases.     

Fractal structure of the crystalline-nuclei boundaries in 2D colloidal crystallization: Computer simulations

By performing 2D kinetic Monte Carlo simulations of colloidal crystallization we found that the boundaries of the crystalline nuclei are not only rough, as obtained by experimentalists, but fractal, whose value (_df$d_f$) we calculated. The corresponding boundary for the crystals, above the critical size (_Nc$N_c$), is also fractal but smoother. A knowledge of the particles coordinates during the crystallization process allows us to calculate the _Nc$N_c$, the line tension (γ) and the chemical potential difference (Δμ) between the two phases. However, different from the experimentalists procedure, we found that the boundary fractalities are needed to derive γ and Δμ.     

Fluxmetric and magnetometric demagnetizing factors for cylinders

Fluxmetric and magnetometric demagnetizing factors, _Nf$N_{\mathrm{f}}$ and _Nm$N_{\mathrm{m}}$, for cylinders along the axial direction are numerically calculated as functions of material susceptibility χ$\chi$ and the ratio γ$\gamma$ of length to diameter. The results have an accuracy better than 0.1% with respect to min(_Nf,m,1-_Nf,m)$\min (N_{\mathrm{f},\mathrm{m}},1-N_{\mathrm{f},\mathrm{m}})$ and are tabulated in the range of 0.01?γ?500$0.01?\gamma ?500$ and -1?χ<∞$-1?\chi <\infty$. _Nm$N_{\mathrm{m}}$ along the radial direction is evaluated with a lower accuracy from _Nm$N_{\mathrm{m}}$ along the axis and tabulated in the range of 0.01?γ?1$0.01?\gamma ?1$ and -1?χ<∞$-1?\chi <\infty$. Some previous results are discussed and several applications are explained based on the new results.     

Exploring self-similarity of complex cellular networks: The edge-covering method with simulated annealing and log-periodic sampling

Song et al. [Self-similarity of complex networks, Nature 433 (2005) 392–395] have recently used a version of the box-counting method, called the node-covering method, to quantify the self-similar properties of 43 cellular networks: the minimal number _NV$N_V$ of boxes of size ?$?$ needed to cover all the nodes of a cellular network was found to scale as the power-law _NV∼(?+1)^-_DV$N_V\sim (?+1{)}^{-D_V}$ with a fractal dimension _DV=3.53±0.26$D_V=3.53\pm 0.26$. We implement an alternative box-counting method in terms of the minimum number _NE$N_E$ of edge-covering boxes which is well-suited to cellular networks, where the search over different covering sets is performed with the simulated annealing algorithm. The method also takes into account a possible discrete scale symmetry to optimize the sampling rate and minimize possible biases in the estimation of the fractal dimension. With this methodology, we find that _NE$N_E$ scales with respect to ?$?$ as a power-law _NE∼?^-_DE$N_E\sim {?}^{-D_E}$ with _DE=2.67±0.15$D_E=2.67\pm 0.15$ for the 43 cellular networks previously analyzed by Song et al. [Self-similarity of complex networks, Nature 433 (2005) 392–395]. Bootstrap tests suggest that the analyzed cellular networks may have a significant log-periodicity qualifying a discrete hierarchy with a scaling ratio close to 2.     

Magnetic,dielectric and magnetoelectric properties of new family of orthorhombic multiferroic Eu1−xYxMNO3 manganites

Multiferroic ground states with a spatially modulated antiferromagnetic structure and electric polarization have been revealed in Eu_1−xY_xMnO₃ (0.2?x?0.5$0.2?x?0.5$) single crystals. While the slightly substituted (x?0.1$x?0.1$) compounds exhibited a transition from the incommensurate (IC) to the canted antiferromagnetic (CAF) state at _TCA<_TN$T_{\mathrm{CA}}<T_{\mathrm{N}}$, the transitions from IC to commensurate ferroelectric (C/FE) phase were observed at _Tlock<_TN$T_{\mathrm{lock}}<T_{\mathrm{N}}$ for x>0.2$x>0.2$. Various phase transitions were observed in the magnetic fields up to 250 kOe along a, b, c axes by magnetization, magnetostriction and electric polarization measurements which show an existence of a spontaneous electric polarization below T_lock.     

New limits on radiative sterile neutrino decays from a search for single photons in neutrino interactions

It has been recently shown that excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino _νh${\nu }_h$ produced in _νμ${\nu }_{\mu }$ neutral-current-like neutrino interactions. If the _νh${\nu }_h$ exist, it would be also produced by the _νμ${\nu }_{\mu }$ beam from the CERN SPS in the neutrino beam line shielding. The _νh${\nu }_h$?s would penetrate the shielding and be observed through the _νh→γν${\nu }_h\to \gamma \nu$ decay followed by the photon conversion into e⁺e⁻$e^{+}{e}^{-}$ pair in the active target of the NOMAD detector. The _νh${\nu }_h$?s could be also produced in the iron of the magnetic spectrometer of the CHORUS detector, located just in front of NOMAD. Considering these two sources of _νh${\nu }_h$?s we set new constraints on _νh${\nu }_h$ properties and exclude part of the LSND/MiniBooNE _νh${\nu }_h$ parameter space using bounds on single photons production in neutrino reactions recently reported by the NOMAD Collaboration. We find that broad bands in the parameter space are still open for more sensitive searches for the _νh${\nu }_h$ in future neutrino experiments.     

Structural and electronic properties of a single C chain doped zigzag BN nanoribbons

The effects of single C-chain on the stability, structural and electronic properties of zigzag BN nanoribbons (ZBNNRs) were investigated by first-principles calculations. C-chain was expected to dope at B-edge for all the ribbon widths _Nz$N_z$ considered. The band gaps of C-chain doped _Nz$N_z$-ZBNNR are narrower than that of perfect ZBNNR due to new localized states induced by C-chain. The band gaps of _Nz$N_z$-ZBNNR-C(n  ) are direct except for the case of C-chain position n=2$n=2$. Band gaps of BN nanoribbons are tunable by C-chain and its position n, which may endow the potential applications of BNNR in electronics.     

Random ballistic growth and diffusion in symmetric spaces

Sequential ballistic deposition (BD) with next-nearest-neighbor (NNN) interactions in a N  -column box is viewed as a time-ordered product of (N×N)$(N\times N)$-matrices consisting of a single _sl2${\mathit{sl}}_2$-block which has a random position along the diagonal. We relate the uniform BD growth with the diffusion in the symmetric space _HN=SL(N,R)/SO(N)$H_N=\mathit{SL}(N,R)/\mathit{SO}(N)$. In particular, the distribution of the maximal height of a growing heap is connected with the distribution of the maximal distance for the diffusion process in _HN$H_N$. The coordinates of _HN$H_N$ are interpreted as the coordinates of particles of the one-dimensional Toda chain. The group-theoretic structure of the system and links to some random matrix models are also discussed.     

Leading logarithmic large-x resummation of off-diagonal splitting functions and coefficient functions

We analyze the iterative structure of unfactorized partonic structure functions in the large-x   limit, and derive all-order expressions for the leading-logarithmic off-diagonal splitting functions Pgq$P_{\mathrm{gq}}$ and Pqg$P_{\mathrm{qg}}$ and the corresponding coefficient functions C_?,q$C_{?,\mathrm{q}}$ and C_2,g$C_{2,\mathrm{g}}$ in Higgs- and gauge-boson exchange deep-inelastic scattering. The splitting functions are given in terms of a new function not encountered in perturbative QCD so far, and vanish maximally in the supersymmetric limit CA−CF→0$C_A-C_F\to 0$. The coefficient functions do not vanish in this limit, and are given by simple expressions in terms of the above new function and the well-known leading-logarithmic threshold exponential. Our results also apply to the evolution of parton fragmentation functions and semi-inclusive e⁺e⁻$e^{+}{e}^{-}$ annihilation.     

The extended Higgs system in R-symmetric supersymmetry theories

The Higgs sector is extended in R  -symmetric supersymmetry theories by two iso-doublets R_d,u$R_{d,u}$ which complement the standard iso-doublets H_d,u$H_{d,u}$. We have analyzed masses and interactions of these novel states and describe their [non-standard] decay modes and their production channels at the LHC and e⁺e⁻$e^{+}{e}^{-}$ colliders.     

Properties of fermion mixings in intersecting D-brane models

We consider the Yukawa couplings for quarks and leptons in the context of Pati–Salam model using intersecting D-brane models where the Yukawa coupling matrices are rank one in a simple choice of family replication. The CKM mixings can be explained by perturbing the rank 1 matrix using higher order terms involving new Higgs fields available in the model. We show that the near bi-large neutrino mixing angles can be naturally explained, choosing the light neutrino mass matrix to be type II seesaw dominant. The predicted value of U_e3$U_{e3}$ is in the range ?0.05–0.15$?0.05\text{–}0.15$. In the quark sector, V_cb$V_{cb}$ is naturally close to the strange/bottom quark mass ratio and we obtain an approximate relation V_ubV_cb?(ms/mb)²V_us$V_{ub}{V}_{cb}?{(m_s/m_b)}^2{V}_{us}$. The geometrical interpretations of the neutrino mixings are also discussed.     

Tsallis statistics and magnetospheric self-organization

In this study we use Tsallis non-extensive statistics for a new understanding the magnetospheric dynamics and the magnetospheric self-organization during quiet and intensive superstorm periods. The _qsens$q_{sens}$, _qstat$q_{stat}$, and _qrel$q_{rel}$ indices set known as the Tsallis q$q$-triplet was estimated during both quiet and strongly active periods, as well as the correlation dimensions and Lyapunov exponents spectrum for magnetospheric bulk plasma flows data. The results obtained by our analysis clearly indicate the magnetospheric phase transition process from a high-dimensional quiet SOC state to a low-dimensional global chaotic state when superstorm events are developed. During such a phase transition process the non-extensive statistical character of the magnetospheric plasma is strengthened as the values of the q$q$-triplet indices changes obtaining higher values than their values during the quiet periods.     

Conductance oscillations in a mesoscopic ring threaded by a harmonically time-dependent magnetic flux

We consider a microscopic model for a one-dimensional ring of non-interacting electrons threaded by a magnetic flux of the form Φ(t)=Φ₀+Φ₁cos(Ω₀t)$\Phi (t)={\Phi }_0+{\Phi }_1\cos ({\Omega }_{0}t)$. The ring is attached to two reservoirs at which a bias voltage is applied. We focus on small amplitudes of Φ₁${\Phi }_1$, and we analyze the behavior of the conductance as a function of Φ₀${\Phi }_0$. We solve the problem by means of non-equilibrium Green function techniques.     

TCAD assessment of Gate Electrode Workfunction Engineered Recessed Channel (GEWE-RC) MOSFET and its multi-layered gate architecture,Part II: Analog and large signal performance evaluation

Part I of this paper dealt with the hot carrier reliability evaluation of Gate Electrode Workfunction Engineered Recessed Channel (GEWE-RC) MOSFET involving channel recession and gate electrode workfunction engineering integration onto the conventional MOSFET, using an ATLAS device simulator. It was demonstrated that with the gate stack architecture incorporated onto the GEWE-RC MOSFET and tuning of various structural design parameters such as gate length (_LG$L_G$), negative junction depth (NJD), substrate doping (_NA$N_A$), gate metal workfunction, substrate bias (_VSUB$V_{SUB}$), drain bias (_VDS$V_{DS}$) and gate oxide permittivity (_εox2${\epsilon }_{ox2}$), excellent hot carrier immunity can be achieved in terms of conduction band offset, reduced electron velocity, electron temperature, hot electron injected gate current and impact ionization substrate current. This paper focuses on the analog and large signal performance metrics in terms of linearity, intermodulation distortion, device efficiency and speed-to-power dissipation design parameters. Moreover, the paper also discusses the effect of gate stack architecture and various design parameters such as _LG$L_G$, NJD, _NA$N_A$, gate metal workfunction and _εox2${\epsilon }_{ox2}$ for different substrate (_VSUB$V_{SUB}$) and drain to source (_VDS$V_{DS}$) voltages. The work, thus, proves the effectiveness of GEWE-RC for RFICs with a higher efficiency, better linearity performance; and designing and modeling of power amplifiers.