BiS2 - based superconductivity in F-substituted NdOBiS2

Source: arXiv

ABSTRACT We have successfully synthesized a new BiS2-based superconductor NdOBiS2 with
F-doping. This compound is composed of superconducting BiS2 layers and blocking
NdO layers, which indicates that the BiS2 layer is the one of the common
superconducting layers like the CuO2 layer of cuprates or Fe-As layer of
Fe-based superconductors. We can obtain NdO1-xFxBiS2 with bulk
superconductivity by a solid-state reaction under ambient pressure. Therefore,
NdO1-xFxBiS2 should be the suitable material to elucidate the mechanism of
superconductivity in the BiS2-layer.

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    ABSTRACT: We discuss the electronic structure, lattice dynamics, and electron-phonon interaction of the newly discovered superconductor LaO0.5F0.5BiS2 using density-functional-based calculations. A strong Fermi surface nesting at k=(π,π,0) suggests a proximity to charge-density-wave instability and leads to imaginary harmonic phonons at this k point associated with in-plane displacements of S atoms. Total energy analysis resolves only a shallow double-well potential well preventing the appearance of static long-range order. Both harmonic and anharmonic contributions to electron-phonon coupling are evaluated and give a total coupling constant λ≃0.85, prompting this material to be a conventional superconductor contrary to structurally similar FeAs materials.
    Physical review. B, Condensed matter 03/2013; 87(11). · 3.66 Impact Factor
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    ABSTRACT: Using the density-functional perturbation theory with structural optimization, we investigate the electronic structure, phonon spectra, and superconductivity of the BiS2-based layered compounds LaO1−xFxBiS2. For LaO0.5F0.5BiS2, the calculated electron-phonon coupling constant is equal to λ = 0.8, and the obtained Tc 9.1 K is very close to its experimental value, indicating that it is a conventional electron-phonon superconductor.
    EPL (Europhysics Letters) 02/2013; 101(4):47002. · 2.27 Impact Factor
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    ABSTRACT: Resistive and magnetic properties have been measured in BiS2-based samples CeO1-xFxBiS2 with a systematic substitution of O with F (0<x<0.6). In contrast to the band-structure calculations, it is found that the parent phase of CeOBiS2 is a bad metal instead of a band insulator. By doping electrons into the system, it is surprising to find that superconductivity appears together with a semiconducting normal state. This evolution is clearly different from the cuprate and the iron pnictide systems, and is interpreted as approaching the Pomeranchuk transition with a von Hove singularity and the possible charge-density-wave instability. Furthermore, ferromagnetism, which may arise from the Ce magnetic moments, has been observed in the low-temperature region in all samples, suggesting the coexistence of superconductivity and ferromagnetism in the superconducting samples.
    Physical review. B, Condensed matter 12/2012; · 3.66 Impact Factor

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