Analysis of nonlinear conductivity of point contacts on the base of FeSe in the normal and superconducting state

Автор(и)

  • Yu.G. Naidyuk B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
  • N.V. Gamayunova B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
  • O.E. Kvitnitskaya B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkov 61103, Ukraine
  • G. Fuchs Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e.V., Postfach 270116 Dresden D-01171, Germany
  • D.A. Chareev Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka 142432, Moscow District, Russia
  • A.N. Vasiliev Low Temperature Physics and Superconductivity Department, Physics Faculty, M.V. Lomonosov Moscow State University Moscow 119991, Russia

DOI (Low Temperature Physics):


https://doi.org/10.1063/1.4939153%20

Ключові слова:

iron-chalcogenide superconductors, point-contacts, Andreev reflection spectroscopy, energy gap.

Анотація

Nonlinear conductivity of point contacts (PCs) on the base of FeSe single crystals has been investigated. Measured dV/dI dependencies demonstrate the prevailing contribution to the PC conductivity caused by the degraded surface. Superconducting (SC) feature in dV/dI like a sharp zero-bias minimum develops for relatively low ohmic PCs, where the deep areas of FeSe are involved. Analysis of dV/dI has shown that the origin of the zero-bias minimum is connected with the Maxwell part of the PC resistance, what masks energy dependent spectral peculiarities. Even so, we have found the specific features in dV/dI — the sharp side maxima, which may have connection to the SC gap, since their position follows the BCS temperature dependence. Exploring the dV/dI spectra of the rare occurrence with Andreev-like structure, the two gaps with Δ = 2.5 and 3.5 meV were identified.

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Опубліковано

2015-11-17

Як цитувати

(1)
Yu.G. Naidyuk, N.V. Gamayunova, O.E. Kvitnitskaya, G. Fuchs, D.A. Chareev, and A.N. Vasiliev, Analysis of nonlinear conductivity of point contacts on the base of FeSe in the normal and superconducting state, Low Temp. Phys. 42, (2015) [Fiz. Nizk. Temp. 42, 42-48, (2015)] DOI: https://doi.org/10.1063/1.4939153 .

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