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

Abstract

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 Delta = 2.5 and 3.5 meV were identified.

10 pages, 6 figs., accepted for publication in "Low Temperature Physics"

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Cited by in corpus (5)

• Metamorphoses of electronic structure of FeSe-based superconductors (Review article)
• Proximity and Josephson effects in microstructures based on multiband superconductors
• Doubling of the critical temperature of FeSe observed in point contacts
• The superconducting gaps in FeSe studied by soft point-contact Andreev reflection spectroscopy
• Sub-kelvin Andreev reflection spectroscopy of superconducting gaps in FeSe