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Magnetic pair breaking in superconducting Ba1−xKxBiO3 investigated by magnetotunneling

P. Szabó, P. Samuely, A. G. M. Jansen, J. Marcus, P. Wyder

DOI 10.1103/PhysRevB.62.3502 · Physical Review B

T1

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Abstract

The de Gennes–Maki theory of gapless superconductivity for dirty superconductors is used to interpret the tunneling measurements on the strongly type-II high-Tc oxide superconductor Ba1−xKxBiO3 in high magnetic fields up to 30 T. We show that this theory is applicable at all temperatures and in a wide range of magnetic fields starting from 50% of the upper critical field Bc2. In this magnetic field range the measured superconducting density of states (DOS) has the simple energy dependence as predicted by de Gennes from which the temperature dependence of the pair-breaking parameter α(T), or Bc2(T), has been obtained. The deduced temperature dependence of Bc2(T) follows the Werthamer-Helfand-Hohenberg prediction for classical type-II superconductors in agreement with our previous direct determination. The amplitudes of the deviations in the DOS depend on the magnetic field via the spatially averaged superconducting order parameter which has a square-root dependence on the magnetic field. Finally, the second Ginzburg-Landau parameter κ2(T) has been determined from the experimental data.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
Ba1-xKxBiO3

Archive — visibility unverified

Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

23Pressure unresolvedmidpoint
Ba1-xKxBiO3

Archive — visibility unverified

Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

23Pressure unresolvedmidpoint

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