Посилання:Scanning-tunneling microscopy/spectroscopy and break-junction tunneling spectroscopy of FeSe₁–xTex / T. Ekino, A. Sugimoto, A.M. Gabovich // Физика низких температур. — 2013. — Т. 39, № 3. — С. 343–353. — Бібліогр.: 50 назв. — англ.
Підтримка:We thank the Natural Science Center for Basic Research
and Development, Hiroshima University for EPMA analysis
and supplying liquid helium. This work was supported by a Grand-in-Aid for Scientific Research (245403770) of the
Ministry of Education, Culture, Sports, Science, and Technology
(MEXT) of Japan. The work was partially supported
by the Project N 8 of the 2012-2014 Scientific Cooperation
Agreement between Poland and Ukraine.
The iron-chalcogenide superconductor FeSe₁–xTex (0.5 < x < 1) was investigated by scanning-tunneling microscopy/
spectroscopy (STM/STS) and break-junction techniques. In the STM topography of the samples, randomly
distributed Te and Se surface atomic structure patterns correlate well with the bulk composition, demonstrating
that nanoscale surface features directly reflect bulk properties. The high-bias STS measurements
clarified the gap-like structure at ≈ 100–300 meV, which is consistent with the break-junction data. These highenergy
structures were also found in sulfur substituted FeS₀.₁Te₀.₉. Possible origin of such spectral peculiarities
is discussed. The superconducting gap 2Δ ≈ 3.4 ± 0.2 meV at temperature T = 4.2 K was found in the break junction
of FeSe₁–xTex with the critical temperature Tc ≈ 10 K. The corresponding characteristic gap to Tc ratio
2Δ/kBTc ≈ 4 ± 0.2 indicates moderate superconducting coupling (kB is the Boltzmann constant).