Fluctuation-induced diamagnetism above the superconducting transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">MgB</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Mosqueira, J.; Ramallo, M. V.; Currás, S. R.; Torrón, C.; Vidal, F.

doi:10.1103/physrevb.65.174522

Cited by 21 publications

(20 citation statements)

References 24 publications

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“…where e is the electron charge,h is the reduced Planck constant, t = ln(T/T c ) is the reduced temperature, B LD = (2ξ c (0)/d) 2 is the Lawrence-Doniach [49] layering parameter, ξ c (0) is the Ginzburg-Landau coherence length amplitude in the out-of-plane direction ( 1.1 Å in YBCO [44,45]), d is the superconducting layer periodicity length ( 5.85 Å in YBCO [44,45]) and c is a high-temperature cutoff constant 0.7 [43,44,50,51]. Closer to T c , for T BKT T 1.01T c we find the strong phase fluctuation regime, dominated by the Berezinskii-Kosterkitz-Thouless (BKT) transition temperature T BKT (∼ T c − 2K in YBCO) [42,52].…”

Section: Rounding Of R(t) Near the Superconducting Transition Due To Critical Phenomenamentioning

confidence: 99%

Calculations of Some Doping Nanostructurations and Patterns Improving the Functionality of High-Temperature Superconductors for Bolometer Device Applications

et al. 2020

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We calculate the effects of doping nanostructuration and the patterning of thin films of high-temperature superconductors (HTS) with the aim of optimizing their functionality as sensing materials for resistive transition-edge bolometer devices (TES). We focus, in particular, on spatial variations of the carrier doping into the CuO 2 layers due to oxygen off-stoichiometry, (that induce, in turn, critical temperature variations) and explore following two major cases of such structurations: First, the random nanoscale disorder intrinsically associated to doping levels that do not maximize the superconducting critical temperature; our studies suggest that this first simple structuration already improves some of the bolometric operational parameters with respect to the conventional, nonstructured HTS materials used until now. Secondly, we consider the imposition of regular arrangements of zones with different nominal doping levels (patterning); we find that such regular patterns may improve the bolometer performance even further. We find one design that improves, with respect to nonstructured HTS materials, both the saturation power and the operating temperature width by more than one order of magnitude. It also almost doubles the response of the sensor to radiation.

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Section: Rounding Of R(t) Near the Superconducting Transition Due To Critical Phenomenamentioning

confidence: 99%

Calculations of Some Doping Nanostructurations and Patterns Improving the Functionality of High-Temperature Superconductors for Bolometer Device Applications

et al. 2020

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“…Since then, different attempts have been proposed to extend to high-ε these meanfield descriptions, including the introduction of different versions of the conventional momentum cutoff, [8-24, 49-65, 67, 93-101, 124] or an ad hoc penalization (not a cutoff) of the short-wavelength fluctuation modes that already takes into account the quantum localization. [125,126] However, none of these earlier proposals lead to the vanishing of all fluctuation modes above a well-defined temperature, T onset . Such a T onset was proposed in Ref.…”

Section: Onset Temperature Of the Superconducting Fluctuationsmentioning

confidence: 99%

The conductivity and the magnetization around Tc in optimally-doped YBa$_2$Cu$_3$O$_{7-δ}$ revisited: quantitative analysis in terms of fluctuating superconducting pairs

Rey,

Carballeira,

Doval

et al. 2019

Preprint

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We first present detailed measurements of the rounding behavior around the superconducting transition temperature, T c , of the in-plane electrical conductivity, magnetoconductivity and magnetization, including the low and moderate magnetic field regimes, in a high-quality single crystal and a thin film of the prototypical optimally-doped YBa 2 Cu 3 O 7−δ (OPT Y-123), in which the inhomogeneity effects are minimized. Then, it is presented a comparison of these experimental data with the phenomenological Ginzburg-Landau (GL) approach that takes into account the unavoidable contribution of the fluctuating pairs, the only theoretical scenario allowing at present to analyze these roundings at the quantitative level. These analyses demonstrate that the measured rounding effects around T c may be explained quantitative and consistently in terms of the GL scenario, even up to the rounding onset temperatures if the quantum localization, associated with the shrinkage of the superconducting wavefunction, is taken into account. The implications of our results on the pseudogap physics of optimally-doped cuprates are also discussed.

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“…Note that no published fluctuation measurement has been done on a single crystal. Studies of the fluctuation magnetization [22,23,25] and specific heat [24] have been performed on misoriented powders or polycrystalline samples and the fluctuation conductivity have been studied on thin films [21,26].…”

Section: Introductionmentioning

confidence: 99%

“…situation concerning fluctuations in MgB 2 is somewhat uncertain. Early papers on the fluctuation conductivity [21], magnetization [22,23], and specific heat [24] described the experimental data using conventional single-band theory. However, for analysis of the fluctuating magnetization very close to the transition temperature T c in Ref.…”

Section: Introductionmentioning

confidence: 99%

Fluctuations in two-band superconductors in strong magnetic field

Koshelev

Varlamov

2014

Supercond. Sci. Technol.

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We consider the behaviour of the fluctuating specific heat and conductivity in the vicinity of the upper critical field line for a two-band superconductor. Multiple-band effects are pronounced when the bands have very different coherence lengths. The transition to superconductive state is mainly determined by the properties of the rigid condensate of the "strong" band, while the "weak" band with a large coherence length of the Cooper pairs causes the nonlocality in fluctuation behaviour and break down of the simple Ginzburg-Landau picture. As expected, the multiple-band electronic structure does not change the functional forms of dominating divergencies of the fluctuating corrections when the magnetic field approaches the upper critical field. The temperature dependence of the coefficients, however, is modified. The large in-plane coherence length sets the field scale at which the upper critical field has upward curvature. The amplitude of fluctuations and fluctuation width enhances at this field scale due to reduction of the effective z-axis coherence length. We also observe that the apparent transport transition displaces to lower temperatures with respect to the thermodynamic transition. Even though this effect exists already in a single-band case at sufficiently high fields, it may be strongly enhanced in multiband materials.

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Fluctuation-induced diamagnetism above the superconducting transition inMgB2

Cited by 21 publications

References 24 publications

Calculations of Some Doping Nanostructurations and Patterns Improving the Functionality of High-Temperature Superconductors for Bolometer Device Applications

Calculations of Some Doping Nanostructurations and Patterns Improving the Functionality of High-Temperature Superconductors for Bolometer Device Applications

The conductivity and the magnetization around Tc in optimally-doped YBa$_2$Cu$_3$O$_{7-δ}$ revisited: quantitative analysis in terms of fluctuating superconducting pairs

Fluctuations in two-band superconductors in strong magnetic field

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