Nonexponential London Penetration Depth of FeAs-Based Superconducting RFeAsO0.9F0.1 (R=La, Nd) Single Crystals

被引：85
作者：
Martin, C.
Tillman, M. E.
Kim, H.
Tanatar, M. A.
Kim, S. K.
Kreyssig, A.
Gordon, R. T.
Vannette, M. D.
Nandi, S.
Kogan, V. G.
Bud'ko, S. L.
Canfield, P. C.
Goldman, A. I.
Prozorov, R. [1 ]
机构：
[1] Iowa State Univ, Ames Lab, Ames, IA 50011 USA
来源：
PHYSICAL REVIEW LETTERS | 2009年 / 102卷 / 24期
关键词：
SMFEASO0.8F0.2; ANISOTROPY; FIELD; GAPS; MGB2;
D O I：
10.1103/PhysRevLett.102.247002
中图分类号：
O4 [物理学];
学科分类号：
0702 ;
摘要：
The superconducting penetration depth lambda(T) has been measured in RFeAsO0.9F0.1 (R=La, Nd) single crystals (R-1111). In Nd-1111, we find an upturn in lambda(T) upon cooling and attribute it to the paramagnetism of the Nd ions, similar to the case of the electron-doped cuprate Nd-Ce-Cu-O. After the correction for paramagnetism, the London penetration depth variation is found to follow a power-law behavior, Delta lambda(L)(T)proportional to T-2 at low temperatures. The same T-2 variation of lambda(T) was found in nonmagnetic La-1111 crystals. Analysis of the superfluid density and of penetration depth anisotropy over the full temperature range is consistent with two-gap superconductivity. Based on this and on our previous work, we conclude that both the RFeAsO (1111) and BaFe2As2 (122) families of pnictide superconductors exhibit unconventional two-gap superconductivity.
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