Evolution of superconducting gaps in Th-substituted Sm(1-x)Th(x)OFeAs studied by multiple Andreev reflection spectroscopyстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 24 мая 2017 г.
Аннотация:Using intrinsic multiple Andreev reflections effect (IMARE) spectroscopy, we studied SnS contacts in the layered oxypnictide superconductors Sm(1-x)Th(x)OFeAs with various thorium doping and critical temperatures Tc = 21-54 K. We observe a scaling between both superconducting gaps and Tc. The determined BCS-ratio for the large gap 2Δ_L/kTc = 5.0-5.7 and its eigen BCS-ratio (in a hypothetical case of zero interband coupling) 2Δ_L/kTc^L = 4.1-4.6 both exceeding the weak-coupling limit 3.52, and for the small gap 2Δ_S/kTc = 1.2-1.6 remain nearly constant within all the Tc range studied. The temperature dependences Δ_{L,S}(T) agree well with a two-band BCS-like Moskalenko and Suhl model. We prove intraband coupling to be stronger than interband coupling, whereas and Coulomb repulsion constants mu* are finite in Sm-based oxypnictides.