Effect of disordering on properties of high-temperature superconductors

Aleksashin, B. A.; Berger, I. F.; Verkhovskiǐ, S. V.; Воронин, В. И.; Goshchitskii, B. N.; Давыдов, С. А.; Kar’kin, A. E.; Кожевников, В. Л.; Mirmelshtein, A. V.; Mikhalyov, K.N.; Parkhomenko, V. D.; Cheshnitskiǐ, S. M.

doi:10.1016/0921-4534(88)90622-3

Cited by 33 publications

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“…Under irradiation localized moment contribution appears in the magnetic susceptibility of high-T c oxides 237,170 . In the temperature range from T c to 300K χ(T ) is satisfactorily described by Curie-Weiss type dependence: χ(T ) = χ 0 + C/(T − Θ).…”

Section: B High-t C Superconductorsmentioning

confidence: 99%

“…Now let us consider the experiments on controllable disordering of high-temperature superconductors. Already the first experiments on low temperature (T = 80K) fast neutron irradiation of ceramic samples of high-T c systems [237][238][239][240][241]243 has shown that the growth of structural disorder leads to a number of drastic changes in their physical properties:…”

Section: B High-t C Superconductorsmentioning

confidence: 99%

“…The observed variation of ρ as a function both of fluence and of temperature can be described by the following empirical formula 237 :…”

Section: B High-t C Superconductorsmentioning

confidence: 99%

“…170 and below). Detailed neutron diffraction studies of structural changes in irradiated samples were also performed 237,170,247 . These investigations has shown definitely that there are no oxygen loss in Y Ba 2 Cu 3 O 6.95 during low temperature irradiation.…”

Section: B High-t C Superconductorsmentioning

confidence: 99%

“…18 cm −2 , including superconducting samples 237,170,[238][239][240][241] . These data are shown in Fig.34 170 for the dependence of ρ(T = 80K) on Φ obtained from measurements made directly during the process of irradiation.…”

Section: B High-t C Superconductorsmentioning

confidence: 99%

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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 Superconductorsmentioning

confidence: 99%