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Jeong, Gawoon; Kye, J. I.; Chun, Seung‐Hyun; Lee, Sergey; Lee, S. I.; Khim, Z. G.

doi:10.1103/physrevb.49.15416

Cited by 27 publications

(7 citation statements)

References 9 publications

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“…The STM tunneling data for the Hg cuprates reported in this work are indicated by solid circles and underlined labels. STM tunneling data from previous works 42,47 are indicated by open circles. The break-junction tunneling data on BSCCO, YBCO, its 60 K phase ͑YBCO-60 K͒ and La 2Ϫx Sr x CuO 4Ϫx ͑LSCO͒ are indicated by solid squares.…”

Section: Data Interpretation and Discussionmentioning

confidence: 99%

“…41 Jeong et al, observed two types of spectra, one BCS-like with a large gap and the other showing heavily smeared double-gap features, in polycrystalline Hg-1223 by scanning tunneling spectroscopy ͑STS͒. 42 Rossel et al also observed smeared gap spectra by STS in melted polycrystalline Hg-1223, but enhanced-peak spectra with very large gap values in single crystals of Pb-doped Hg-1234. 43 Differences in sample quality and measurement technique could have contributed to this spectral variety.…”

Section: Introductionmentioning

confidence: 92%

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Quasiparticle tunneling spectra of the high-Tcmercury cuprates: Implications of thed-wave two-dimensional van Hove scenario

Wei

Tsuei²,

Bentum

et al. 1998

Phys. Rev. B

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Quasiparticle tunneling measurements of the high-temperature superconductors HgBa 2 Ca nϪ1 Cu n O 2nϩ2ϩ␦ (Hg-12(nϪ1)n,nϭ1,2,3) are considered in the context of d x 2 Ϫy 2 symmetry of the superconducting order parameter and a two-dimensional ͑2D͒ van Hove singularity ͑vHs͒ related to saddle points in the electronic band structure. Normal-metal-insulator-superconductor tunneling spectra taken at 4.2 K with a scanning tunneling microscope on Hg-1212 c-axis epitaxial films, as well as on Hg-1201 and Hg-1223 polycrystalline samples, show distinct gap characteristics which cannot be easily reconciled with the simple s-wave BCS density of states. The data are analyzed with the nodal d-wave gap function ⌬ k ϭ⌬ 0 (cos k x Ϫcos k y )/2 and the 2D tight-binding electronic dispersion k ϭϪ2t(cos k x ϩcos k y )ϩ4tЈ(cos k x cos k y )Ϫ, using the quasiparticle tunneling formalism for elastic and specular transmission. The analysis indicates a highly directional and energy-dependent spectral weighting, related to the gap anisotropy and band-structure dependence of the tunneling matrix element ͉T͉ 2 , and successfully explains the observed gap spectra. Values for the d-wave gap maximum are determined to be ⌬ 0 Ϸ33, 50, and 75 meV, respectively, for optimally doped Hg-1201, Hg-1212, and Hg-1223, corresponding to reduced-gap ratios of 2⌬ 0 /k B T c Ϸ7.9, 9.5, and 13. These ratios are substantially larger than the BCS weak-coupling limit of 3.54. A comparison with data from other high-T c cuprates indicates an overall trend of 2⌬ 0 /k B T c rising with T c , in violation of BCS universality.

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Section: Data Interpretation and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Quasiparticle tunneling spectra of the high-Tcmercury cuprates: Implications of thed-wave two-dimensional van Hove scenario

Wei

Tsuei²,

Bentum

et al. 1998

Phys. Rev. B

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“…|ε b | and g have to be obtained from Eqs. (60,63,65) (with n B = 0, C a = C a0 and ε A0 = −∆). The situation ∆/T c = 4 corresponds to the critical case described in Section VI G.…”

Section: B Tunneling Characteristicsmentioning

confidence: 99%

Hypothesis of two-dimensional stripe arrangement and its implications for the superconductivity in high-Tccuprates

Fine

2004

Phys. Rev. B

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The hypothesis that holes doped into high-Tc cuprate superconductors organize themselves in two-dimensional (2D) array of diagonal stripes is discussed, and, on the basis of this hypothesis, a new microscopic model of superconductivity is proposed and solved. The model describes two kinds of hole states localized either inside the stripes or in the antiferromagnetic domains between the stripes. The characteristic energy difference between these two kinds of states is identified with the pseudogap. The onset of superconductivity is caused by the interaction, which is assumed to be mediated by the transverse fluctuations of stripes. The superconducting (SC) order parameter predicted by the model has two components, whose quantum phases exhibit a complex dependence on the the center-of-mass coordinate. The model predictions for the tunneling characteristics and for the dependence of the critical temperature (Tc) on the superfluid density show good quantitative agreement with a number of experiments. The model, in particular, predicts that the SC peaks in the tunneling spectra are asymmetric, only when ∆/Tc > 4, where ∆ is the SC gap. It is also proposed that, at least in some high-Tc cuprates, there exist two different superconducting states corresponding to the same doping concentration and the same critical temperature. Finally, the checkerboard pattern in the local density of states observed by scanning tunneling microscopy in Bi2Sr2CaCu2O 8+δ is interpreted as coming from the states localized around the centers of stripe elements forming the 2D superstructure.

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“…The line has been prepared on the basis of the formula (1). The experimental data: (a) Jeong et al[60], (b) Rossel et al[61].…”

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confidence: 99%

On the Ratio of the Energy Gap Amplitude to the Critical Temperature for Cuprates

Szczȩśniak

Durajski

2014

Acta Phys. Pol. A

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The model for the cuprates based on the modified electron-phonon pairing mechanism has been tested. For this purpose, the superconductors with high value of the critical temperature have been taken into consideration. In particular: YBa2Cu3O7−y, HgBa2CuO4+y, HgBa2Cu1−xZnxO4+y, and HgBa2Ca2Cu3O8+y. It has been shown that the dependence of the ratio R1 ≡ 2∆ (0) tot /kBTC on the doping (p) can be properly predicted in the framework of the presented theory; the symbol ∆ (0) tot denotes the energy gap amplitude at the temperature of zero kelvin, and TC is the critical temperature. The numerical results have been supplemented by the formula which describes the function R1(p).

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Energy gap of the high-TcsuperconductorHgBa2

Cited by 27 publications

References 9 publications

Quasiparticle tunneling spectra of the high-Tcmercury cuprates: Implications of thed-wave two-dimensional van Hove scenario

Quasiparticle tunneling spectra of the high-Tcmercury cuprates: Implications of thed-wave two-dimensional van Hove scenario

Hypothesis of two-dimensional stripe arrangement and its implications for the superconductivity in high-Tccuprates

On the Ratio of the Energy Gap Amplitude to the Critical Temperature for Cuprates

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