Measurement of electron density of states at the Fermi level in YBCO by means of an “oxygen pump”

Gerbstein, Yu.M.; Timoshchenko, N. E.; Chudnovskii, F. A.

doi:10.1016/0921-4534(89)90543-1

Cited by 3 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using a much lower chemical potential in the S, µ ∼ 35 meV, 45 and an upper cut-off frequency comparable to the spin fluctuation energy in the high-T c cuprates, ω + ∼ 0.04 eV to 0.15 eV, 32,33,46 ω − = µ, and parameters otherwise as for the s-wave case, we solve the gap equations for a d-wave superconductor. First of all, the effect of the d-wave gap structure, compared to an s-wave gap, is an overall change in scaling, just as is the case for ∆ 0 (see Appendix C).…”

Section: B D-wave Pairingmentioning

confidence: 99%

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

et al. 2019

View full text Add to dashboard Cite

We study the inverse proximity effect in a bilayer consisting of a thin s-or d-wave superconductor (S) and a topological insulator (TI). Integrating out the topological fermions of the TI, we find that spin-orbit coupling is induced in the S, which leads to spin-triplet p-wave (f -wave) correlations in the anomalous Green's function for an s-wave (d-wave) superconductor. Solving the self-consistency equation for the superconducting order parameter, we find that the inverse proximity effect can be strong for parameters for which the Fermi momenta of the S and TI coincide. The suppression of the gap is approximately proportional to e −1/λ , where λ is the dimensionless superconducting coupling constant. This is consistent with the fact that a higher λ gives a more robust superconducting state. For an s-wave S, the interval of TI chemical potentials for which the suppression of the gap is strong is centered at µTI = ± 2mv 2 F µ, and increases quadratically with the hopping parameter t. Since the S chemical potential µ typically is high for conventional superconductors, the inverse proximity effect is negligible except for t above a critical value. For sufficiently low t, however, the inverse proximity effect is negligible, in agreement with what has thus far been assumed in most works studying the proximity effect in S-TI structures. In superconductors with low Fermi energies, such as high-Tc cuprates with d-wave symmetry, we again find a suppression of the order parameter. However, since µ is much smaller in this case, a strong inverse proximity effect can occur at µTI = 0 for much lower values of t. Moreover, the onset of a strong inverse proximity effect is preceded by an increase in the order parameter, allowing the gap to be tuned by several orders of magnitude by small variations in µTI. arXiv:1808.03650v3 [cond-mat.supr-con]

show abstract

Section: B D-wave Pairingmentioning

confidence: 99%

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

et al. 2019

View full text Add to dashboard Cite

show abstract

How resistive must grain boundaries in polycrystalline superconductors be, to limitJ_c?

Wang

Raine

Hampshire

2017

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Although we can use misorientation angle to distinguish the grain boundaries that can carry high critical current density in high temperature superconductors (HTS) from those that cannot, there is no established normal state property equivalent. In this paper, we explore the superconducting and normal state properties of the grains and grain boundaries of polycrystalline YBa2Cu3O7−x (YBCO) using complementary magnetisation and transport measurements, and calculate how resistive grain boundaries must be to limit in polycrystalline superconductors. The average resistivity of the grain boundaries, in our micro- and nanocrystalline YBCO are 0.12 Ωm and 8.2 Ωm, values which are much higher than that of the grains and leads to huge values of 2 × 103 and 1.6 × 105 respectively. We find that the grain boundaries in our polycrystalline YBCO are sufficiently resistive that we can expect the transport to be several tens of orders of magnitude below the potential current density of the grains in our YBCO samples, as is found experimentally. Calculations presented show that increasing values by ∼2 orders of magnitude in high fields is still possible in all state-of-the-art technological high-field superconductors. We conclude: grain boundary engineering is unlikely to improve sufficiently in randomly aligned polycrystalline YBCO, to make it technologically useful for high-field applications; in low temperature superconducting intermetallics, such as Nb3Sn, large increases in may be achieved by completely removing the grain boundaries from these materials and, as is the case for thin films of Nb, Ba(FeCo)2As2 and HTS materials, by incorporating additional artificial pinning.

show abstract

The high-temperature superconductor gap equation

Verma¹,

Kumari²,

Gupta³

et al. 2019

Phys. Scr.

View full text Add to dashboard Cite

The expressions for superconducting gap (SG) have been derived using the quantum dynamical many-body theory of electron density of states for high-temperature superconductors (HTSs). The developed two-gap equations depend on the temperature, Fermi energy and renormalized electron and phonon energies that emerge as signatures of anharmonic effects. The computation of the SG compared with the Bardeen–Cooper–Schrieffer gap is found to be in good agreement in the low-temperature region with slight deviation near the critical temperature (Tc). The gap equation reveals anisotropic nature and the reduced gap ratio ( for ) is found in the upper limit of the reduced gap ratio for HTSs. Both the SG equations approach the same critical temperature. The pairing potential is derived using the SG equation and numerically analyzed for , which shows that Tc depends on the strength of the pairing potential and we explore the possibilities to elevate the transition temperature Tc.

show abstract

Measurement of electron density of states at the Fermi level in YBCO by means of an “oxygen pump”

Cited by 3 publications

References 0 publications

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

How resistive must grain boundaries in polycrystalline superconductors be, to limitJ_c?

The high-temperature superconductor gap equation

Contact Info

Product

Resources

About

Measurement of electron density of states at the Fermi level in YBCO by means of an “oxygen pump”

Cited by 3 publications

References 0 publications

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

Inverse proximity effect in s -wave and d -wave superconductors coupled to topological insulators

How resistive must grain boundaries in polycrystalline superconductors be, to limitJc?

The high-temperature superconductor gap equation

Contact Info

Product

Resources

About

How resistive must grain boundaries in polycrystalline superconductors be, to limitJ_c?