Low Temperature Physics: 47, 110 (2021); https://doi.org/10.1063/10.0003170
Fizika Nizkikh Temperatur: Volume 47, Number 2 (February 2021), p. 125-131    ( to contents , go back )

Superconducting properties of GdxPb1–xMo6S8(x = 0.5, 0.7, 0.9) compounds

A. V. Terekhov1,2, D. L.   Bashlakov1, I. V. Zolochevskii1, E. V. Khristenko1, A. Zaleski2, E. P. Khlybov3, and S. A. Lachenkov4

1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of UkraineKharkov 61103, Ukraine
E-mail: terekhov.andrii@gmail.com

2W. Trzebiatowski Institute for Low Temperatures & Structure Research PAS, Wroclaw 50-950, Poland

3Vereshchagin Institute for High Pressure Physics of the Russian Academy of Sciences, Troitsk 142190, Russia

4A. A. Baikov Institute of Metallurgy and Materials Science of the Russian Academy of SciencesMoscow 119991, Russia
pos Анотація:2167

Received November 3, 2020, revised November 16, 2020, published online December 25, 2020


For the first time, the temperature dependences of the electrical resistivity ρ(T) were studied in GdxPb1–xMo6S8(х = 0.5, 0.7, 0.9) compounds in the temperature range 4–18 K and magnetic fields up to 14 T. It is shown that the superconducting transition temperature values Tc decrease from 14.6 K for a compound with x = 0.5 to 11.8 K for x  =  0.9.  Experimental  dependences  Hc2(T)   were plotted  and  it  was  found  that  the  theoretical  dependence  Hc2(T)   within the microscopic theory of Werthamer–Helfand–Hohenberg poorly describes the experimental datafor the Gd0.9Pb0.1Mo6S8 compound. At the same time, the fit of Hc2(T) within the Ginzburg–Landau theory is in good  agreement  with  the  experimental  results  for  all  the  studied  samples.  An  explanation  of  the  dependence  Hc2(T)  of  the  studied  samples  from  the  gadolinium  concentration  was  proposed.  The  differential  resistance  for  the  Gd0.5Pb0.5Mo6S8–Ag  heterocontact  with  resistance  RPC≈  2.6 Ω  was  obtained  for  2.6  K  using  point-contact Andreev reflection spectroscopy. As a result, the superconducting gap for Gd0.5Pb0.5Mo6S8 was estimated for the first time to be Δ ≈ 1.95 meV at 2.6 K. The resulting ratio was 2Δ/kTc≈ 3.02, which is lower than the Bardeen–Cooper–Schrieffer value of 3.52 for conventional weakly coupled superconductors.

Key words: ternary molybdenum chalcogenides, superconductivity, upper critical magnetic field, Werthamer–Helfand–Hohenberg theory, Ginzburg–Landau theory, orbital critical field, paramagnetic critical field, point-contact Andreev reflection spectroscopy, superconducting gap

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