Breakdown of Eliashberg Theory for Two-Dimensional Superconductivity in the Presence of Disorder

Dynes, R. C.; White, Alice E.; Graybeal, J. M.; Garno, J. P.

doi:10.1103/physrevlett.57.2195

Cited by 142 publications

(57 citation statements)

References 12 publications

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“…In their pioneering work, Anderson 1 and Abrikosov and Gorkov 2 claimed that nonmagnetic impurities have no considerable effect on the thermodynamic properties of s-wave superconductors; this result is known as "Anderson theorem" for weakly disordered dirty superconductors. Since the discovery and elucidation of the localization phenomenon, 3 corrections to the Anderson theorem have been intensively investigated both experimentally [4][5][6][7][8] and theoretically. [9][10][11][12][13][14][15][16][17][18] Within mean-field theory, it has been shown that if one neglects Coulomb interactions, pairing survives below the mobility edge until the localization length reaches a critical value.…”

Section: Introductionmentioning

confidence: 99%

“…Motivated by the thin-film physics, more experimental studies focused on the nature of the density of states ͑DOS͒ and the quasiparticle energy gap of disordered single layer superconducting thin films [5][6][7]23,26,25,28 and superconductornormal-metal ͑SN͒ bilayers. 41,48,49 Interestingly, these studies found a broadening of the BCS peak and also a subgap density of states.…”

Section: Introductionmentioning

confidence: 99%

“…41,48,49 Interestingly, these studies found a broadening of the BCS peak and also a subgap density of states. 6,23,25,26,28,48 Of particular interest to us is the work in Ref. 49, which studied a thin SN bilayer system, and found a surprisingly low value of the ratio of the energy gap to T c , in contradiction to standard BCS theory, and the theory of proximity [50][51][52] where it is claimed that the energy gap-T c ratio should be bounded from below by ϳ3.…”

Section: Introductionmentioning

confidence: 99%

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Effect of inhomogeneous coupling on BCS superconductors

2008

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We investigate the influence of inhomogeneity in the pairing coupling constant U͑r ជ͒ on dirty BCS superconductors, focusing on T c , the order parameter ⌬͑r ជ͒, and the energy gap E g ͑r ជ͒. Within mean-field theory, we find that when the length scale of the inhomogeneity is comparable to or larger than the coherence length, the ratio 2E g / T c is significantly reduced from that of a homogeneous superconductor, while in the opposite limit, this ratio stays unmodified. In two dimensions, when strong phase fluctuations are included, the KosterlitzThouless temperature T KT is also studied. We find that when the inhomogeneity length scale is much larger than the coherence length, 2E g / T KT can be larger than the usual BCS value. We use our results to qualitatively explain recent experimental observation of a surprisingly low value of 2E g / T c in thin films.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of inhomogeneous coupling on BCS superconductors

2008

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“…Интересные результаты для од-нородных пленок Pb были получены в работе [23] посредством туннель-ных измерений. Было установлено, что с ростом беспорядка отношение 2∆/kТ c остается практически посто-янным (рис.…”

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“…2. Зависимость Т c (а) и 2∆/kТ c (б) от R для однородных пленок Pb [23]. Цифры вверху означают типичные тол-щины пленок в ангстремах !…”

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Superconductivity and localization of electrons in disordered two-dimensional metal systems

Белевцев¹

1990

Usp. Fiz. Nauk

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Support of polaronic states and charge carrier concentrations of YBa₂Cu₃O₇_‐y ceramics by oxygen and Mn₂O₃ impurity

Kurtul,

Yildirim,

Turgay

et al. 2024

Microscopy Res & Technique

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The influence of oxygen and Mn2O3 impurity addition intervals 0.01 ≤ x ≤ 0.30 on the basic electrical conductivity, stabilization, crystallinity quality, grain boundary couplings, structural, orbital hybridization mechanisms, and superconducting properties of YBa2Cu3O7‐yMnx ceramics has extensively been analyzed by electrical resistivity, X‐ray diffraction investigations, and related theoretical results. It has been found that there is a strong link between the production conditions and fundamental characteristic features. All the results deduced have enabled us to discuss the variation of electron–electron and electron–phonon interactions, order parameter for super‐electrons and cooper‐pairs, organization of Cu–O coordination, homogeneities of oxidation states, microscopic structural problems, electronic density states, and grain boundary couplings between the adjacent layers in the YBa2Cu3O7‐y ceramics. Similarly, we have discussed the change in the formation of pairing mechanisms and bipolarons in the polarizable lattices in the microdomain clusters. The results have shown that both the presence of oxygen and optimum manganese impurity of x = 0.07 led to the enhancement in the fundamental characteristic features related to the basic physical, quantum mechanical, and thermodynamics features. Thus, the material produced at the most ideal conditions has exhibited the best orthorhombic crystal structure with the distortion degree of 6.419 × 10−3, paring mechanism, and crystallinity quality due to the development of orthorhombicity and oxygen ordering degree. Namely, the addition of optimum manganese impurity has organized the Cu–O coordination and stabilized the crystal structure as much as possible. Numerically, the sample prepared with x = 0.07 Mn ions has displayed the largest crystallite size, c‐axis length, residual resistivity ratio, onset, and offset critical temperatures of 10.977, 11.723 Å, 73 nm, 98.320 K, and 100.504 K, respectively. Conversely, the same material has demonstrated the smallest oxygen ordering degree of 6.714, strain of 44.015 × 10−3, and a‐ and b‐axis lengths of 3.792 and 3.841 Å. On the other hand, the oxygen‐free annealing condition and excess manganese impurity have completely damaged the whole mechanism because of the phase transition from orthorhombic to tetragonal (structural O–T transition) crystal structure. To sum up, the oxygen and optimum manganese impurity have encouraged the YBa2Cu3O7‐y superconductors to use in much more application fields.Research Highlights The presence of oxygen and an optimal level of Mn2O3 impurity in YBa2Cu3O7‐y superconductors improved superconducting properties. The optimal level of Mn2O3 impurity promotes standard metallic characteristics. Ideal process conditions lead to the formation of super‐electrons and cooper‐pairs, expanding the superconducting energy gap. Optimal conditions lead to the expansion of orthorhombic distortion symmetry and average crystallite size. The excess manganese impurity results in a metal‐to‐insulator transition.

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Breakdown of Eliashberg Theory for Two-Dimensional Superconductivity in the Presence of Disorder

Cited by 142 publications

References 12 publications

Effect of inhomogeneous coupling on BCS superconductors

Effect of inhomogeneous coupling on BCS superconductors

Superconductivity and localization of electrons in disordered two-dimensional metal systems

Support of polaronic states and charge carrier concentrations of YBa₂Cu₃O₇_‐y ceramics by oxygen and Mn₂O₃ impurity

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Breakdown of Eliashberg Theory for Two-Dimensional Superconductivity in the Presence of Disorder

Cited by 142 publications

References 12 publications

Effect of inhomogeneous coupling on BCS superconductors

Effect of inhomogeneous coupling on BCS superconductors

Superconductivity and localization of electrons in disordered two-dimensional metal systems

Support of polaronic states and charge carrier concentrations of YBa2Cu3O7‐y ceramics by oxygen and Mn2O3 impurity

Contact Info

Product

Resources

About

Support of polaronic states and charge carrier concentrations of YBa₂Cu₃O₇_‐y ceramics by oxygen and Mn₂O₃ impurity