Singular behavior of the Emery model with O-O hopping for high-T$\mathsf{_c}$ superconductors

Mean field slave boson (MFSB) solution is found analytically for the Emery model of the high-T_c cuprates with infinite interaction U_d on the Cu-site and finite O-O hopping t', in addition to the Cu-O hopping t₀. The solution is found for arbitrary Cu-O charge transfer energy and small doping , assuming only t' < 0 for the insulating phase, appropriate for the superconducting cuprates. It is shown analytically that the Brinkmann-Rice metal-insulator transition is preserved, though shifted to higher values of . To the leading order in t', the transition conserves its t'=0 triple point nature with complete electron-hole symmetry with respect to doping. This symmetry is broken by logarithmically small terms related to the t'-induced shift of the chemical potential of the half-filled band from the van Hove singularity. Qualitative change in the behavior of the effective charge transfer energy is found at finite t' for large . The prerequisite to MFSB solution is the discussion of the singularities in the 3-band dispersion of the Emery model. The range of parameters leading to the touching of two bands is determined analytically, showing that it is wider than known before. The anticrossing (rather than touching) is however consistent with the observed Fermi surfaces, leading to the MFSB theory with t' < 0. The detailed comparison of the theory with the angle-resolved photoemission spectroscopy data in La Sr CuO₄, Bi₂Sr₂CaCuO and YBa₂Cu₃O is finally given, using the properties of the resonant band of the physical fermions, discussed in the companion paper. Fast evolution of the band-structure with doping is explained for LSCO. The three-band fits for Bi2212 and Y123 are equally good, although the Luttinger sum rule is not obeyed there.Received: 30 May 2002, Published online: 23 July 2003PACS:   71.18.+y Fermi surface: calculations and measurements; effective mass, g factor - 74.72.Dn La-based cuprates - 74.25.Jb Electronic structure - 79.60.-i Photoemission and photoelectron spectra     

The optimal velocity traffic flow models with open boundaries

The effects of the open boundaries on the dynamical behavior of the optimal velocity traffic flow models with a delay time allowing the car to reach its optimal velocity is studied using numerical simulations. The particles could enter the chain with a given injecting rate probability , and could leave the system with a given extracting rate probability . In the absence of the variation of the delay time , it is found that the transition from unstable to metastable and from metastable to stable state occur under the effect of the probabilities rates and . However, for a fixed value of , there exist a critical value of the extraction rate above which the wave density disappears and the metastable state appears and a critical value above which the metastable state disappears while the stable state appears. and depend on the values of and the variation of the delay time . Indeed and increase when increasing and/or decreasing . The flow of vehicles is calculated as a function of , and for a fixed value of . Phase diagrams in the ( ) plane exhibits four different phases namely, unstable, metastable, stable. The transition line between stable phase and the unstable one is curved and it is of first order type. While the transition between stable (unstable) phase and the metastable phase are of second order type. The region of the metastable phase shrinks with increasing the variation of the delay time and disappears completely above a critical value .Received: 23 July 2003, Published online: 8 December 2003PACS: 05.50. + q Lattice theory and statistics (Ising, Potts, etc.) - 64.60.Cn Order-disorder transformations; statistical mechanics of model systems - 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) - 82.20.Wt Computational modeling; simulation     

Scaling behavior of jamming fluctuations upon random sequential adsorption

It is shown that the fluctuations of the jamming coverage upon Random Sequential Adsorption (RSA) ( ), decay with the lattice size according to the power-law , with ,where D is the dimension of the substrate and is the fractal dimension of the set of sites belonging to the substrate where the RSA process actually takes place. This result is in excellent agreement with the figure recently reported by Vandewalle et al. [Eur. Phys. J. B 14, 407 (2000)], namely for the RSA of needles with D = 2 and , that gives . Furthermore, our prediction is in excellent agreement with different previous numerical results. The derived relationships are also confirmed by means of extensive numerical simulations applied to the RSA of dimers on both stochastic and deterministic fractal substrates.Received: 17 October 2003, Published online: 8 December 2003PACS: 05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion - 02.50.-r Probability theory, stochastic processes, and statistics     

Continuum bound states K L, D 1(2420), D s1(2536), and their partners K S, D 1(2400), D * sJ(2463)

The very recently observed D^*_sJ(2463) meson is described as a bound state in a unitarised meson model, owing its existence to the strong OZI-allowed coupling to the nearby S-wave threshold. By the same non-perturbative mechanism, the narrow axial-vector D_s1(2536) resonance shows up as a quasi-bound-state partner embedded in the continuum. With the same model and parameters, it is also shown that the preliminary broad 1 ⁺ D₁(2400) resonance and the established narrow 1 ⁺ D₁(2420) may be similar partners, as a result of the strong OZI-allowed coupling to the nearby S-wave threshold. The continuum bound states D₁(2420) and D_s1(2536) are found to be mixtures of 33% and 67% , whereas their partners D₁(2400) and D^*_sJ(2463) have more or less the opposite -state content, but additionally with some or admixture, respectively. The employed mechanism also reproduces the ratio of the K_L-K_S mass difference and the K_S width, by describing K_L as a bound state embedded in the continuum. The models results for states containing one b quark are also discussed.Received: 7 June 2003, Revised: 20 October 2003, Published online: 18 December 2003PACS: 12.40.Yx, 14.40.Aq, 14.40.Lb, 13.25.Es, 13.25.Ft, 13.75.Lb     

Aggregate size distributions in migration driven growth models

The kinetics of aggregate growth through reversible migrations between any two aggregates is studied. We propose a simple model with the symmetrical migration rate kernel at which the monomers migrate from the aggregates of size k to those of size j. The results show that for the case, the aggregate size distribution approaches a conventional scaling form; moreover, the typical aggregate size grows as in the case and as in the case. We also investigate another simple model with the asymmetrical rate kernel ( ), which exhibits some scaling properties quite different from the symmetrical one. The aggregate size distribution satisfies the conventional scaling form only in the case of and , and the typical aggregate size grows as .Received: 14 October 2003, Published online: 23 December 2003PACS: 82.20.-w Chemical kinetics and dynamics - 68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation - 89.75.Da Systems obeying scaling laws     

$\mathsf{\sqrt{3}}$ linear structures in the Te/Ni(111) system

Surface structures in the Te/Ni(111) system are revealed by using reflection high-energy electron diffraction combined with X-ray and ultraviolet photoelectron spectroscopies. At a 0.33 mono-layer (ML)-Te/Ni(111) surface, a reversible structural phase transition is observed with a transition temperature T_c of 380 C. The diffraction pattern from the low temperature phase is accompanied by streaks. The high and low temperature phases are characterized by and rectangle, respectively. The mechanism of the phase transition is explained by the order-disorder transition with a rumpled chain model. Both 0.51 ML- and 0.44 ML-Te/Ni(111) surfaces exhibit the complex diffraction patterns accompanied by diffuse streaks. These surface structures are characterized by the rectangle and , respectively. All diffuse streaks obtained at the above surfaces are consistently interpreted in the view of the ill-ordered arrangements of the well-ordered linear chains. It is shown that the linear structure is the key in the Te/Ni(111) system.Received: 1 December 2003, Published online: 20 April 2004PACS: 61.14.Hg Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED) - 68.65.-k Low-dimensional, mesoscopic, and nanoscale systems: structure and nonelectronic properties - 64.60.Cn Order-disorder transformations; statistical mechanics of model systems     

Thermal conductivity of doped $\mathsf{La_2CuO_4}$ as an example for heat transport by optical phonons in complex materials

We investigate the phonon thermal conductivity of doped based on out-of-plane thermal conductivity measurements. When room temperature is approached the temperature dependence of strongly deviates from the T^-1-decrease which is usually expected for heat transport by acoustic phonons. Instead, decreases much weaker or even increases with rising temperature. Simple arguments suggest that such unusual temperature dependencies of are caused by heat transport via dispersive optical phonons.Received: 20 October 2003, Published online: 20 April 2004PACS: 66.70. + f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves - 74.72.Dn La-based cuprates - 44.10. + i Heat conduction     

Spin-gap phase in the extended t — J chain

We study the one-dimensional deformed model in terms of the continuum field theories. We found that at low doping concentration and far away from the phase separation regime, there are two phases: the Luttinger liquid and the Luther-Emery liquid, depending on or , where . Moreover, the singlet superconducting correlations are dominant in the Luther-Emery liquid.Received: 12 October 2003, Published online: 19 February 2004PACS: 71.10.Fd Lattice fermion models - 71.10.Hf Non-Fermi-liquid ground states - 74.20.Mn Non-conventional mechanisms     

On the Meissner effect in a superconductor with 4-fermion attraction

A presence of a Meissner-Ochsenfeld effect in a gas of spin 1/2 fermions with an interaction , where is a volume of a region in real space which is taken by thesystem and with , satisfying Fermi anticommutation relations, is investigated. The effect proves to be weaker than in BCS by a factor 3/4 at T = 0, implying a greater penetration depth of external magnetic field. V ₄ is nonzero only within a thin layer of 1-fermion energies around the chemical potential .Received: 14 June 2004, Published online: 12 October 2004PACS: 74.20.-z Theories and models of superconducting state - 74.20.Fg BCS theory and its development     

\alpha-decay spectroscopy of light odd-odd Bi isotopes - II: 186Bi and the new nuclide 184Bi

Alpha-decay of the new nuclide ¹⁸⁴Bi has been studied in the complete-fusion reaction ⁹³Nb(⁹⁴Mo, 3n)¹⁸⁴Bi at the velocity filter SHIP. The evaporation residues were separated in-flight and subsequently identified on the basis of recoil- , recoil- - analysis and excitation functions measurements. Two -decaying isomeric states in ¹⁸⁴Bi with half-life values of 13(2) ms and 6.6(1.5) ms were identified. The -branching ratio of ¹⁸⁰Tl was deduced for the first time as . Improved data on the fine-structure -decay of ¹⁸⁶Bi were obtained in the ⁹³Nb(⁹⁵Mo, 2n)¹⁸⁶Bi reaction. A similarity of the decay energies and half-life values of ^184,186Bi is pointed out and a possible explanation for this effect is suggested.Received: 14 March 2003, Revised: 29 April 2003, Published online: 2 September 2003PACS: 23.60.+e decay - 27.70.+q - 27.80.+w K. Heyde: Present address: EP-ISOLDE, CERN, CH-1211, Geneva 23, Switzerland.     

Nucleation of superconductivity in finite metallic multilayers: Effect of the symmetry

The influence of the finite dimensions of superconducting metallic multilayers on H-T phase diagram is studied. It is established that the geometrical symmetry of the samples determines crucially the dependencies. For samples where the symmetry plane is in the middle of the superconducting layer the values are, for temperatures close to T _c , larger than the values of the samples for which the symmetry plane lies in the middle of the normal layer. The results are analysed on the basis of the Ginzburg-Landau approach and are explained by considering the different symmetry of the wave function describing the system. The experimental results are in good agreement with the elaborated model, which takes into account the actual symmetry of the samples.Received: 23 July 2004, Published online: 5 November 2004PACS: 74.78.Fk Multilayers, superlattices, heterostructures - 74.20.De Phenomenological theories (two-fluid, Ginzburg-Landau, etc.) - 74.45. + c Proximity effects; Andreev effect; SN and SNS junctions     

Spin-dependent transport in films composed of Co clusters and C $_{\mathsf{60}}$ fullerenes

Granular films of Co-cluster/C₆₀ mixtures have been prepared by the co-deposition of well defined Co clusters (mean diameter 4.5 nm) and C₆₀ fullerenes onto a cold ( 35 K) substrate. Films having a Co cluster volume fraction show a resistivity , typical for tunneling with a Coulomb barrier. The tunneling magnetoresistance (TMR) has a value of TMR ( % for and is decreasing by almost one order of magnitude going to . We explain this unusual decrease of the TMR with increasing as caused by electron-doping of the C₆₀ fullerenes due to the known charge transfer process occurring between transition metal surface and C₆₀. Increasing electron doping may lead to an increasing probability for spin-flip processes within the tunneling barrier, resulting in a decrease of the TMR.Received: 17 March 2004, Published online: 3 August 2004PACS: 75.47.-m Magnetotransport phenomena; materials for magnetotransport - 73.40.Gk Tunneling - 73.40.Rw Metal-insulator-metal structures     

Irreversible adsorption from dilute polymer solutions

We study irreversible polymer adsorption from dilute solutions theoretically. Universal features of the resultant non-equilibrium layers are predicted. Two broad cases are considered, distinguished by the magnitude of the local monomer-surface sticking rate Q: chemisorption (very small Q) and physisorption (large Q). Early stages of layer formation entail single-chain adsorption. While single-chain physisorption times are typically micro- to milli-seconds, for chemisorbing chains of N units we find experimentally accessible times , ranging from seconds to hours. We establish 3 chemisorption universality classes, determined by a critical contact exponent: zipping, accelerated zipping and homogeneous collapse. For dilute solutions, the mechanism is accelerated zipping: zipping propagates outwards from the first attachment, accelerated by occasional formation of large loops which nucleate further zipping. This leads to a transient distribution of loop lengths s up to a maximum size after time t. By times of order the entire chain is adsorbed. The outcome of the single-chain adsorption episode is a monolayer of fully collapsed chains. Having only a few vacant sites to adsorb onto, late-arriving chains form a diffuse outer layer. In a simple picture we find for both chemisorption and physisorption a final loop distribution and density profile whose forms are the same as for equilibrium layers. In contrast to equilibrium layers, however, the statistical properties of a given chain depend on its adsorption time; the outer layer contains many classes of chain, each characterized by a different fraction of adsorbed monomers f. Consistent with strong physisorption experiments, we find the f values follow a distribution .Received: 13 January 2003, Published online: 8 July 2003PACS: 82.35.-x Polymers: properties; reactions; polymerization - 05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion - 68.08.-p Liquid-solid interfaces     

Phenomenological model of nonlinear dielectric losses related to the intrinsic conductivity of dielectrics

A phenomenological approach was applied to the dynamics of the intrinsic electric conductivity of dielectrics in an electric field in order to analyze its contribution to dielectric losses. The proposed differential equation contains only two parameters - the effective time of conductivity decay in an electric field, and , the time describing the recovery rate of the conductivity after switching off the field. The proposed approach predicts a linear dependence of specific conductivity of dielectrics on the sample thickness, as experimentally confirmed by Du Pont [1] for Teflon FEP. The field and time (or frequency) dependences of intrinsic conductivity and related dependences of dielectric losses were calculated, analyzed and illustrated with the published experimental data. The results show that the discussed contribution in dielectric losses is characterized by two hyperbolas (instead of one) while the distance between the branches depends on the intensity of applied electric field.Received: 3 November 2003, Published online: 29 June 2004PACS: 72.20.Ht High-field and nonlinear effects - 72.80.Sk Insulators - 77.22.Gm Dielectric loss and relaxation     

Interface transparency of Nb/Pd layered systems

We have investigated, in the framework of proximity effect theory, the interface transparency of superconducting/normal metal layered systems which consist of Nb and high paramagnetic Pd deposited by dc magnetron sputtering. The obtained value is relatively high, as expected by theoretical arguments. This leads to a large value of the ratio although Pd does not exhibit any magnetic ordering.Received: 12 December 2003, Published online: 20 April 2004PACS: 74.45. + c Proximity effects; Andreev effect; SN and SNS junctions - 74.78.Fk Multilayers, superlattices, heterostructuresS.L. Prischepa: Permanent address: State University of Computer Science and RadioElectronics, P. Brovka street 6, 220600, Minsk, Belarus     

Interpreting remanence isotherms: a Preisach-based study

Numerical simulations of the field dependence of the isothermal remanent moment (IRM) and the thermoremanent moment (TRM) are presented, based on a Preisach formalism which decomposes the free energy landscape into an ensemble of thermally activated, temperature dependent, double well subsystems, each characterized by a dissipation field H _d and a bias field H _s . The simulations show that the TRM approaches saturation much more rapidly than the corresponding IRM and that, as a consequence, the characteristics of the IRM are determined primarily by the distribution of dissipation fields, as defined by the mean field and the dispersion , while the characteristics of the TRM are determined primarily by a mixture of the mean dissipation field and the dispersion of bias fields . The simulations also identify a regime , where the influence of on the TRM is negligible, and hence where the TRM and the IRM provide essentially independent scans of the Preisach distribution along the two orthogonal H _s and H _d directions, respectively. The systematics established by the model simulations are exploited to analyze TRM and IRM data from a mixed ferromagnetic perovskite Ca_0.4Sr_0.6RuO₃, and to reconstruct the distribution of characteristic fields H _d and H _s , and its variation with temperature.Received: 16 April 2004, Published online: 12 August 2004PACS: 75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects - 75.60.-d Domain effects, magnetization curves, and hysteresis     

Electrical resistivity in the ferromagnetic metallic state of La-Ca-MnO\mathsf{_{3}}: Role of electron-phonon interaction

The temperature-dependent resistivity of the perovskite manganites La_1-x Ca _x MnO₃, with x = 0.33, is theoretically analysed within the framework of the classical electron-phonon model of resistivity, i.e., the Bloch-Gruneisen model. Due to inherent acoustic (low-frequency) phonons ( as well as high-frequency optical phonons ( , the contributions to the resistivity have first been estimated. The acoustic phonons of the oxygen-breathing mode yield a relatively larger contribution to the resistivity compared to the contribution of optical phonons. Furthermore, the nature of phonons changes around T = 167 K exhibiting a crossover from an acoustic to optical phonon regime with elevated temperature. The contribution to resistivity estimated by considering both phonons, i.e. and , when subtracted from thin film data, infers a power temperature dependence over most of the temperature range. The quadratic temperature dependence of is understood in terms of electron-electron scattering. Moreover, in the higher temperature limit, the difference can be varies linearly with T ^4.5 in accordance with the electron-magnon scattering in the double exchange process. Within the proposed scheme, the present numerical analysis of temperature dependent resistivity shows similar results as those revealed by experiment.Received: 8 April 2004, Published online: 12 August 2004PACS: 5.47.Gk Colossal magnetoresistance - 72.15.-v Electronic conduction in metals and alloys - 74.25.Kc Phonons - 75.30.Ds Spin wavesD. Varshney: dvboson.sop@dauniv.ac.in     

Scale dependent partitioning of one-dimensional aperiodic set diffraction

We give a multiresolution partition of pure point parts of diffraction patterns of one-dimensional aperiodic sets. When an aperiodic set is related to the Golden Ratio, denoted by , it is well known that the pure point part of its diffractive measure is supported by the extension ring of , denoted by . The partition we give is based on the formalism of the so called -integers, denoted by . The set of -integers is a selfsimilar set obeying , . The pure point spectrum is then partitioned with respect to this Russian doll like sequence of subsets . Thus we deduce the partition of the pure point part of the diffractive measure of aperiodic sets.Received: 24 March 2004, Published online: 12 July 2004PACS: 61.44.Br Quasicrystals - 61.10.Dp Theories of diffraction and scattering     

Measurement of inclusive jet cross sections in photoproduction at HERA

Inclusive jet cross sections are measured in photoproduction at HERA using the H1 detector. The data sample of events in the kinematic range of photon virtualities and photon-proton centre-of-mass energies represents an integrated luminosity of . Jets are defined using the inclusive algorithm. Single- and multi-differential cross sections are measured as functions of jet transverse energy E_T ^jet and pseudorapidity in the domain and . The cross sections are found to be in good agreement with next-to-leading order perturbative QCD calculations corrected for fragmentation and underlying event effects. The cross section differential in E_T ^jet, which varies by six orders of magnitude over the measured range, is compared with similar distributions from colliders at equal and higher energies.Received: 24 February 2003, Revised: 26 May 2003, Published online: 11 July 2003     

Structural,electronic, and optical properties of beryllium monochalcogenides

The results of first-principles theoretical study of the structural, electronic and optical properties of beryllium monochalcogenides BeTe, BeSe and BeS, performed using the full potential linearized augmented plane wave (FP-LAPW) method are presented. The calculated structural parameters and band gaps compare very well with previous theoretical results. The trends of the band gap pressure coefficients and volume deformation potentials for these II-VI compounds are investigated. The linear pressure coefficients for the X and band gaps increase with decrease in anion atomic weight. The dependence of the direct and indirect band gaps on the relative change of lattice constant are found to follow almost the same type of trends in each of these compounds. The volume deformation potential ( ) for the direct ( ) and indirect ( ) gaps are positive, but negative for the indirect ( ) gap. Furthermore, , for transitions decreases with increase in anion atomic number whereas , increases. The optical properties have also been calculated. From the reflectivity spectra, the compounds will be useful for optical applications. The variation of the band gaps with respect to the application of pressure and the origin of some of the peaks in the optical spectra are discussed in terms the calculated electronic structure.Received: 26 September 2003, Published online: 18 June 2004PACS: 71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.) - 71.15.Mb Density functional theory, local density approximation, gradient and other corrections - 71.20.Nr Semiconductor compounds