Possible Multigap Superconductivity in SmFeAsO0.8F0.2: A Point-contact Andreev-reflection Spectroscopy Study

被引：6
|
作者：
Daghero, D. [1 ,2 ]
Tortello, M. [1 ,2 ]
Gonnelli, R. S. [1 ,2 ]
Stepanov, V. A. [3 ]
Zhigadlo, N. D. [4 ]
Karpinski, J. [4 ]
机构：
[1] Politecn Torino, Dipartimento Fis, I-10129 Turin, Italy
[2] Politecn Torino, CNISM, I-10129 Turin, Italy
[3] Russian Acad Sci, PN Lebedev Phys Inst, Moscow 119991, Russia
[4] ETHZ, Solid State Phys Lab, CH-8093 Zurich, Switzerland
来源：
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM | 2009年 / 22卷 / 06期
基金：
俄罗斯基础研究基金会;
关键词：
Fe-As superconductors; Point-contact spectroscopy; Andreev reflection; Multiband superconductivity; GAP;
D O I：
10.1007/s10948-009-0480-y
中图分类号：
O59 [应用物理学];
学科分类号：
摘要：
We discuss the results of point-contact Andreev-reflection spectroscopy (PCAR) measurements in SmFeAsO0.8F0.2 state-of-the-art polycrystals, with critical temperature T (c)a parts per thousand 53 K. The low-temperature conductance curves show clear peaks at about 7 meV and additional shoulders at 16-20 meV. Their shape is similar to that of PCAR spectra in MgB2 and suggests the presence of two superconducting energy gaps even in this Fe-based superconductor. The fit of the conductance curves with a two-band BTK model, up to T (c), further supports this indication in spite of a marked asymmetry in the conductance curves for positive/negative bias. The gaps obtained from the fit are Delta(1)=6.15 +/- 0.45 meV and Delta(2)=18 +/- 3 meV, and they follow a nice BCS-like temperature dependence, closing both at the same T (c). Our results are discussed in comparison with experimental and theoretical results in this and other Fe-based superconductors.
引用
收藏
页码：543 / 547
页数：5
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