Strong thermal fluctuations in cuprate superconductors in magnetic fields above<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>T</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math>

Jiang, Xujiang; Li, Dingping; Rosenstein, Baruch

doi:10.1103/physrevb.89.064507

Cited by 25 publications

(49 citation statements)

References 62 publications

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“…compares reasonably well with experiments for value of UV momentum cutoff of order Λ = 0.25/ξ , deduced from the fluctuation diamagnetism [14] for somewhat different materials. Another feature is the downward curvature of the inverse magnetic penetration depth within a temperature range below the critical point that is much wider than the critical region.…”

Section: Comparison With Experiments On Penetration Depth Of High T Csupporting

confidence: 57%

Covariant gaussian approximation in Ginzburg–Landau model

Wang

Kao

et al. 2017

Annals of Physics

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h i g h l i g h t s• A symmetry conserving approximation based on Dyson-Schwinger equations is proposed.• The approximation keeps all the Ward Identities in a theory with continuous symmetry. • The approximation is more accurate than other mean-field type approximations.• The penetration depth of Ginzburg-Landau model shows a downward cusp near T c . a b s t r a c tCondensed matter systems undergoing second order transition away from the critical fluctuation region are usually described sufficiently well by the mean field approximation. The critical fluctuation region, determined by the Ginzburg criterion, |T /T c − 1| ≪ Gi, is narrow even in high T c superconductors and has universal features well captured by the renormalization group method. However recent experiments on magnetization, conductivity and Nernst effect suggest that fluctuations effects are large in a wider region both above and below T c . In particular some ''pseudogap'' phenomena and strong renormalization of the mean field critical temperature T mf can be interpreted as strong fluctuations effects that are nonperturbative (cannot be accounted for by ''gaussian fluctuations''). The physics in a broader region therefore requires more accurate approach. Self consistent methods are generally ''non-conserving'' in the sense that the Ward identities are not obeyed. This is especially detrimental in the symmetry * 229 broken phase where, for example, Goldstone bosons become massive. Covariant gaussian approximation remedies these problems. The Green's functions obey all the Ward identities and describe the fluctuations much better. The results for the order parameter correlator and magnetic penetration depth of the Ginzburg-Landau model of superconductivity are compared with both Monte Carlo simulations and experiments in high T c cuprates.

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Section: Comparison With Experiments On Penetration Depth Of High T Csupporting

confidence: 57%

Covariant gaussian approximation in Ginzburg–Landau model

Wang

Kao

et al. 2017

Annals of Physics

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“…32 Lastly, we briefly comment on a formalism developed in Ref. 10, where the authors also take account of high LLs and use a similar method to the variational method used here. They consider a quasi-two-dimensional system, which is different from an anisotropic three-dimensional system of our interest.…”

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confidence: 99%

Fluctuation diamagnetism in two-band superconductors

Adachi

Ikeda

2016

Phys. Rev. B

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Anomalously large fluctuation diamagnetism around the superconducting critical temperature has been recently observed on iron selenide (FeSe) [S. Kasahara et al., unpublished]. This indicates that superconducting fluctuations (SCFs) play a more significant role in FeSe, which supposedly has twoband structure, than in the familiar single-band superconductors. Motivated by the data in FeSe, SCF-induced diamagnetism is examined in a two-band system, on the basis of a phenomenological approach with a Ginzburg-Landau functional. The obtained results indicate that the SCF-induced diamagnetism may be more enhanced than that in a single-band system due to the existence of two distinct fluctuation modes. Such enhancement of diamagnetism unique to a two-band system seems consistent with the large diamagnetism observed on FeSe, though still far from a quantitative agreement.

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“…18 in which the full derivations of the magnetization formula used below can be found. The basic characteristics of the vortex liquid is the excitation energy gap, which will be denoted by ε in physical energy unit…”

Section: A Modelmentioning

confidence: 99%

“…The critical temperature T c is often smaller than the meanfield critical temperature T Λ due to strong thermal fluctuations on the mesoscopic scale 18 . Within the gaussian approximation the relation is given by…”

Section: A Modelmentioning

confidence: 99%

“…Bulaevskii et al 16 attempted to use the 2D version of the theory to explain the intersection point in Y BCO, however it was subsequently realized that the exact intersection is inconsistent with the strict LLL scaling 17 . When the restriction on the first Landau level was lifted 18 (while still retaining the self-consistent fluctuation theory of the vortex liquid), the Ginzburg Landau (GL) theory extended to layered materials became capable to describe magnetization in LSCO, BSCCO and Y BCO in wide range of fields and temperatures (even above T c ) with small number of parameters. Both experimentally and theoretically it became apparently that the intersection point is never exact.…”

Section: Introductionmentioning

confidence: 99%

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Concurrent intersection point of magnetization and magnetoconductivity curves in strongly fluctuating superconductors

et al. 2017

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The thermal fluctuations contribution to magnetization and magneto-conductivity of type II layered superconductor is calculated in the framework of Lawrence-Doniach model. For numerous high temperature cuprate superconductors, it was discovered that the magnetization dependence on temperature in wide range of fields exhibits an intersection point at a temperature slightly below Tc. We notice a similar intersection point of the magneto-conductivity curves at the approximate same temperature. The phenomenon is explained by strong (non-gaussian) thermal fluctuations with interactions treated using a self-consistent theory. All higher Landau levels should be included. Dimensionality of the fluctuations is defined and the 2D-3D dimensional crossover is the key for the existence of intersection points.

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Strong thermal fluctuations in cuprate superconductors in magnetic fields aboveTc

Cited by 25 publications

References 62 publications

Covariant gaussian approximation in Ginzburg–Landau model

Covariant gaussian approximation in Ginzburg–Landau model

Fluctuation diamagnetism in two-band superconductors

Concurrent intersection point of magnetization and magnetoconductivity curves in strongly fluctuating superconductors

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