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Berthod, Christophe; Fasano, Yanina; Maggio-Aprile, Ivan; Piriou, A.; Giannini, E.; Levy, G.; Fischer, Ø.

doi:10.1103/physrevb.88.014528

Cited by 23 publications

(41 citation statements)

References 104 publications

(123 reference statements)

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“…For a given thermal smearing the low-energy excitations are only affected by the weight of the superconducting channel and the value of Γ, but the height of the coherence peaks can be modified by the coupling of the excitations with spin collective modes detected in the material at energies closer to ∆, as well as by the normal-state band. [16] Therefore, for a better description and fitting of the whole spectral shape of the quasiparticle excitation spectra in CeCoIn 5 , a fitting procedure considering a model that takes into account the coupling with the magnetic susceptibility of the material is required.…”

Section: Resultsmentioning

confidence: 99%

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Fasano

Szabó

Kačmarčı́k

et al. 2018

Physica B: Condensed Matter

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We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of the heavy fermion CeCoIn 5 between 440 mK and 3 K in samples with a bulk T c = 2.25 K. The spectral shape of our low-temperature tunneling data, quite textbook nodal-∆ conductance, allow us to confidently fit the spectra with a dwave density of states considering also a shortening of quasiparticles' lifetime term Γ. The ∆(0) value obtained from the fits yields a BCS ratio 2∆/kT c = 7.73 suggesting that CeCoIn 5 is an unconventional superconductor in the strong coupling limit. The fits also reveal that the height of coherence peaks in CeCoIn 5 is reduced with respect to a pure BCS spectra and therefore the coupling of quasiparticles with spin excitations should play a relevant role. The tunneling conductance shows a depletion at energies smaller than ∆ for temperatures larger than the bulk T c , giving further support to the existence of a pseudogap phase that in our samples span up to T * ∼ 1.2T c . The phenomenological scaling of the pseudogap temperature observed in various families of cuprates, 2∆/kT * ∼ 4.3, is not fulfilled in our measurements. This suggests that in CeCoIn 5 the strong magnetic fluctuations might conspire to close the local superconducting gap at a smaller pesudogap temperature-scale than in cuprates.

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Section: Resultsmentioning

confidence: 99%

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Fasano

Szabó

Kačmarčı́k

et al. 2018

Physica B: Condensed Matter

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“…The most frequently expressed alternative viewpoint [150][151][152][153] attributes the dip-hump structures observed in cuprates [25,55,56] to the extremely strong-coupling ef- Fig. 3, but for BSCCO [146].…”

Section: Results Of Calculations and Discussionmentioning

confidence: 99%

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Gabovich

Войтенко

2016

Low Temperature Physics

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The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples' intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous superconducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa 2 Cu 3 O 7-δ and Bi 2 Sr 2 CaCu 2 O 8+δ . The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-T c superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress. PACS

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“…[1,[9][10][11][12] and references therein. However, we adhere another viewpoint that PG appears in consequence of the formation of paired fermions (local pairs) in HTSCs at T ≤ T * , see e. g. Refs.…”

Section: Introductionmentioning

confidence: 99%

Hydrostatic-pressure effects on the pseudogap in slightly doped YBa2Cu3O7−δ single crystals

Solovjov

Omelchenko

Вовк

et al. 2016

Physica B: Condensed Matter

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The influence of hydrostatic pressure up to P=1.05 GPa on resistivity, excess conductivity σ ′ (T ) and pseudogap ∆ * (T ) is investigated in slightly doped single crystals of Y Ba2Cu3O 7−δ (Tc(P = 0) ≈49.2 K and δ ≈ 0.5). The critical temperature Tc is found to increase with increasing pressure at a rate dTc/dP = +5.1 KGP a −1 , while ρ(300) K decreases at a rate dlnρ/dP = (−19±0.2)% GP a −1 . Near Tc, independently on pressure, the σ ′ (T ) is well described by the Aslamasov-Larkin and HikamiLarkin fluctuation theories, demonstrating a 3D-2D crossover with increase of temperature. The crossover temperature T0 determines the coherence length along the c-axis ξc(0) ≃ (3.43 ± 0.01)Å at P=0, which is found to decrease with increasing P. At the same time, ∆ * and the BCS ratio 2∆ * /kB Tc both increase with increasing hydrostatic pressure at a rate dln∆ * /dP ≈ 0.36 GP a −1 , implying an increase of the coupling strength with increasing P. At low temperatures below Tpair, the shape of the ∆ * (T ) curve is found to be almost independent on pressure. At high temperatures, the shape of the ∆ * (T ) curve changes noticeably with increasing P, suggesting a strong influence of pressure on the lattice dynamics. This unusual behavior is observed for the first time.

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Strong-coupling analysis of scanning tunneling spectra in Bi2Sr2Ca2Cu
Christophe Berthod
¹
,
Yanina Fasano
²
,
Ivan Maggio-Aprile
³

et al.

Cited by 23 publications

References 104 publications

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Hydrostatic-pressure effects on the pseudogap in slightly doped YBa2Cu3O7−δ single crystals

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Strong-coupling analysis of scanning tunneling spectra in Bi2Sr2Ca2CuChristophe Berthod1, Yanina Fasano2, Ivan Maggio-Aprile3 et al.

Cited by 23 publications

References 104 publications

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Unconventional superconductivity in the strong-coupling limit for the heavy fermion system CeCoIn5

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Hydrostatic-pressure effects on the pseudogap in slightly doped YBa2Cu3O7−δ single crystals

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Strong-coupling analysis of scanning tunneling spectra in Bi2Sr2Ca2Cu
Christophe Berthod
¹
,
Yanina Fasano
²
,
Ivan Maggio-Aprile
³

et al.