Point-contact spectroscopic studies on normal and superconducting AFe2As2-type iron-pnictide single crystals
作者： David Mandrus , A. S. Sefat , Suchitra Sebastian , Brian C Sales , J Gillett
DOI: 10.1088/0953-2048/23/5/054009
关键词:
摘要: Point-contact Andreev reflection spectroscopy is applied to investigate the gap structure in iron pnictide single-crystal superconductors of AFe2As2 (A = Ba, Sr) family ('Fe-122'). The observed point-contact junction conductance curves, G(V), can be divided into two categories: one where present for both (Ba0.6K0.4)Fe2As2 and Ba(Fe0.9Co0.1)2As2, other with a V2/3 background universally observed, extending even up 100 meV Sr0.6Na0.4Fe2As2 Sr(Fe0.9Co0.1)2As2. latter also junctions on nonsuperconducting parent compound BaFe2As2 superconducting crystals. Mesoscopic phase-separated coexistence magnetic orders considered explain distinct behaviors samples. For Ba0.6K0.4Fe2As2, double peaks due strongly sloping are frequently point contacts freshly cleaved c-axis surfaces. If normalized using baseline analyzed Blonder–Tinkham–Klapwijk model, data show size ~ 3.0–4.0 2Δ0/kBTc 2.0–2.6, consistent smaller reported LnFeAsO ('Fe-1111'). G(V) curves typically display zero-bias peak.
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