On the localisation of charge carriers and suppression of superconductivity by praseodymium in systems derived from YBa2Cu3O7−d

Infante, C.; Mously, M. K. El; Dayal, R.; Husain, M.; Siddiqi, Saadat Anwar; Ganguly, P.

doi:10.1016/0921-4534(90)90683-6

Cited by 71 publications

(16 citation statements)

References 43 publications

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“…Of these we shall rather arbitrarily quote Refs. [263][264][265][266][267] , which demonstrate the data quite similar, though not necessarily identical, to those described above on different types of systems and obtained by different experimental methods. We note that the effects of chemical chemical disorder are always complicated by the inevitable changes of carrier concentration due to doping effects.…”

Section: B High-t C Superconductorssupporting

confidence: 69%

Superconductivity and localization

1997

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We present a review of theoretical and experimental works on the problem of mutual interplay of Anderson localization and superconductivity in strongly disordered systems. Superconductivity exists close to the metalinsulator transition in some disordered systems such as amorphous metals, superconducting compounds disordered by fast neutron irradiation etc. Hightemperature superconductors are especially interesting from this point of view. Only bulk systems are considered in this review. The superconductor-insulator transition in purely two-dimensional disordered systems is not discussed.We start with brief discussion of modern aspects of localization theory including the basic concept of scaling, self-consistent theory and interaction effects. After that we analyze disorder effects on Cooper pairing and superconducting transition temperature as well as Ginzburg-Landau equations for superconductors which are close to the Anderson transition. A necessary generalization of usual theory of "dirty" superconductors is formulated which allows to analyze anomalies of the main superconducting properties close to disorder-induced metal-insulator transition. Under very rigid conditions superconductivity may persist even in the localized phase (Anderson insulator).Strong disordering leads to considerable reduction of superconducting transition temperature T c and to important anomalies in the behavior of the upper critical field H c2 . Fluctuation effects are also discussed. In the vicinity of Anderson transition inhomogeneous superconductivity appears due to statistical fluctuations of the local density of states.We briefly discuss a number of experiments demonstrating superconductivity close to the Anderson transition both in traditional and high-T c superconductors. In traditional systems superconductivity is in most cases destroyed before metal-insulator transition. In case of high-T c superconductors a number of anomalies show that superconductivity is apparently conserved in the localized phase before it is suppressed by strong enough disorder. The concept of electron localization 1 is basic for the understanding of electron properties of disordered systems 2,3 . In recent years a number of review papers had appeared, extensively discussing this problem [4][5][6][7] . According to this concept introduction of sufficiently strong disorder into a metallic system leads to spatial localization of electronic states near the Fermi level and thus to a transition to dielectric state (Anderson transition). After this transition dc conductivity (at zero temperature, T = 0) vanishes, despite the finite value of electronic density of states at the Fermi level (at least in one-electron approximation).At the same time it is well-known that even the smallest attraction of electrons close to the Fermi level leads to formation of Cooper pairs and the system becomes superconducting at sufficiently low temperatures 8,9 . It is known that the introduction of disorder which does not break the time-reversal invariance (normal, nonm...

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Section: B High-t C Superconductorssupporting

confidence: 69%

Superconductivity and localization

1997

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“…5. The most striking feature in all the spectra of the black BaCO is the presence of modes, both in IR and Raman, in the spectral region where the Cu-O vibrations are found (15)(16)(17). Their intensity ratios are constant in all the investigated samples.…”

Section: And Cuomentioning

confidence: 88%

From Carbonate-Cuprates to Cuprate-Carbonates: The Structural Equivalence of CO3and CuOxGroups in the Ba–Cu–C–O System

Matacotta

Calestani

Migliori

et al. 1997

Journal of Solid State Chemistry

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“…In fact, Ce, Pr, and Tb, in that order, are the three rare earths most easily ionized to the +4 state [8]. Therefore, based on the assumption that the Ce and Pr ions remain in 4+ or a mixed-valence state above 3+, several models have been proposed for explaining the quenching of superconductivity in this system, such as hole filling [9], hole localization [10], and percolation [11]. In another approach, the Pr and Ce retain a valence 3+ and a strong hybridization could break superconducting pairs, causing the depression of T C [12].…”

Section: Introductionmentioning

confidence: 99%

Fluctuation-Induced Conductivity of Polycrystalline (Ho–Ce)Ba 2 Cu 3 O $_{7-\boldsymbol\delta}$ Superconductor

et al. 2011

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We report on systematic conductivity fluctuation measurements on samples of Ho 1−x Ce x Ba 2 Cu 3 O 7−δ with x = 0.00, 0.05, and 0.10. The samples were produced by a standard solid-state reaction method, and the microstructure was analyzed by X-ray diffraction. To identify power-law divergences of the conductivity, the results were analyzed in terms of the temperature derivative of the resistivity dρ/dT and with the logarithmic derivative of the conductivity with respect to temperature −d ln( σ )/dT. It was observed that the critical temperature decreases and that the transition width increases with increasing Ce doping. The data showed the occurrence of a two-stage transition besides the pairing transition splitting, associated with Ce doping and related with the occurrence of a phase separation. Above the critical temperature, the Gaussian and critical regimes were observed. On approaching the zero resistance state, our results showed a power-law behavior that corresponds to a phase transition from a paracoherent to a coherent state of the granular array.

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On the localisation of charge carriers and suppression of superconductivity by praseodymium in systems derived from YBa2Cu3O7−d

Cited by 71 publications

References 43 publications

Superconductivity and localization

Superconductivity and localization

From Carbonate-Cuprates to Cuprate-Carbonates: The Structural Equivalence of CO3and CuOxGroups in the Ba–Cu–C–O System

Fluctuation-Induced Conductivity of Polycrystalline (Ho–Ce)Ba 2 Cu 3 O $_{7-\boldsymbol\delta}$ Superconductor

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