2008/12/05 by D. Daghero, M. Tortello, Mauro Tortello +6 · 1 citation
Business, Management and Accounting · Chemistry · Materials Science · Physics and Astronomy · #Andreev reflection #Band gap #Chemistry #Condensed matter physics #Conductance #Corporate Taxation and Avoidance #Crystallography #Iron-based superconductors research #Materials science #Particle physics #Physics #Physics of Superconductivity and Magnetism #Superconductivity #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.80.060502
published as Physical Review B 80, 060502(R) (2009) · 4 pages, 4 eps color figures
arxiv created 2008/12/05 · openalex publication_date 2009/08/05 · arxiv updated 2011/10/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Point-contact Andreev-reflection spectroscopy measurements were performed in SmFeAsO_1\ensuremath-xFx polycrystals with x=0.09 (Tc\ensuremath≃42 K) and x=0.20 (Tc\ensuremath≃52 K). In all cases the experimental conductance curves reproducibly exhibit low-energy peaks and higher-energy shoulders (at 4--6 and 16--20 meV, respectively, for x=0.20), which indicate the presence of two nodeless superconducting gaps. While the single-band Blonder-Tinkham-Klapwijk model can only reproduce a small central portion of a given conductance curve, the two-gap one accounts remarkably well for the shape of the whole experimental dI/dV vs V curve. The fit of the normalized curves gives \ensuremathΔ1(0)=6.15\ifmmode±\else\textpm\fi0.45 meV and \ensuremathΔ2(0)=18\ifmmode±\else\textpm\fi3 meV for x=0.20, while for x=0.09 the values \ensuremathΔ1(0)=4.9\ifmmode±\else\textpm\fi0.5 meV and \ensuremathΔ2(0)=15\ifmmode±\else\textpm\fi1 meV are obtained. In all cases, both gaps close at the same temperature and follow a BCS-like behavior.