419 research outputs found

    Superconducting properties of the hole-doped three-band \emph{d-p} model studied with minimal-size real-space \emph{d}-wave pairing operators

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    The three-band \emph{d-p} model is investigated by means of Variational Monte-Carlo (VMC) method with the BCS-like wave-function supplemented by the Gutzwiller and Jastrow correlators. The VMC optimization leads to dd-wavewave superconducting state with a characteristic dome-like shape of the order parameter for hole doping δ0.4\delta \lesssim 0.4, in a good agreement with the experimental observations. Also, the off-diagonal pair-pair correlation functions, calculated within VMC, vindicates the results obtained very recently within the diagrammatic expansion of the Gutzwiller wave function method (DE-GWF) [cf. Phys. Rev. B \textbf{99}, 104511 (2019)]. Subsequently, the nature of the dd-wavewave pairing is investigated by means of recently proposed \emph{minimal-size real-space d-wave pairing operators} [Phys. Rev. B \textbf{100}, 214502 (2019)]. An emergence of the long-range superconducting ordering for both dd and pp orbitals is reported by analysing the corresponding off-diagonal pair-pair correlation functions. The dominant character of \emph{d-wave} pairing on dd orbitals is confirmed. Additionally, the trial wave-function is used to investigate the magnetic properties of the system. The analysis of spin-spin correlation functions is carried out and shows antiferromagnetic q=(π,π)\mathbf{q}=(\pi,\pi), short-range order, as expected. For the sake of completeness, the charge gap has been estimated, which for the parent compound takes the value ΔCG1.78±0.51 eV\Delta_{CG}\approx1.78\pm0.51\text{ eV}, and agrees with values reported experimentally for the cuprates

    Methods of risk analysis of telematic objels

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    The paper focuses on basic description of the tunnel as a telematic object and its architecture. Conventional methods of risk analysis of telematic objects are introduced in relation to their safety. New approaches of risk quantification are shown in connection to existing legislation and directives of European Commission

    Field-induced Orbital Patterns in Ferromagnetic Layered Ruthenates

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    We study the evolution of orbital patterns in ferromagnetic layered ruthenates due to the competition of Coulomb interactions, compressive c axis and orthorhombic distortions in the presence of a polarizing orbital field coupled to the angular momentum. By means of the exact diagonalization on a 2x2 cluster and a cluster embedded analysis where inter-plaquette interaction is treated on mean field level, we determine the ground-state phase diagram. Specifically, we demonstrate that, via the activation of two or three of t_2g local orbital configurations, an external field applied along different symmetry directions can lead to inequivalent orbital correlated states. Starting from an antiferro-orbital pattern, for the easy axis case an orbital ordered phase is induced, having strong next nearest neighbors ferro-orbital correlations. Otherwise, a field applied along the hard axis leads a reduction of local orbital moment in a way to suppress the orbital order.Comment: 11 page
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