Multiple Andreev Reflections Spectroscopy of Two-Gap 1111- and 11 Fe-Based Superconductorsстатья
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Дата последнего поиска статьи во внешних источниках: 9 ноября 2013 г.
Аннотация:Using the “break-junction” technique, we prepared and studied superconductor–constriction–superconductor (ScS) nanocontacts in polycrystalline samples of Fe-based superconductors CeO(0.88)F(0.12)FeAs (Ce-1111; Tc^bulk= 41±1 K), LaO(0.9)F(0.1)FeAs (La-1111; Tc^bulk= 28±1 K), and FeSe (Tc^bulk= 12±1 K). We detected two subharmonic gap structures related with multiple Andreev reflections, indicating the presence of two superconducting gaps with the BCS-ratios 2Δ_L/kTc = 4.2 ÷ 5.9 and 2Δ_S/kTc ~ 1 << 3.52, respectively. Temperature dependences of the two gaps Δ_L,S(T) in FeSe indicate a k-space proximity effect between two superconducting condensates. For the studied iron-based superconductors, we found a linear relation between the gap Δ_L and magnetic resonance energy, E_res ≈ 2Δ_L.