Superconducting energy gap and c-axis plasma frequency of (Nd, Sm)FeAsO0.82F0.18 superconductors from infrared ellipsometry

被引：48

作者：

Dubroka, A. ^{[1
,2
]}

Kim, K. W. ^{[1
,2
]}

Roessle, M. ^{[1
,2
]}

Malik, V. K. ^{[1
,2
]}

Drew, A. J. ^{[1
,2
]}

Liu, R. H. ^{[3
,4
]}

Wu, G. ^{[3
,4
]}

Chen, X. H. ^{[3
,4
]}

Bernhard, C. ^{[1
,2
]}

机构：

[1] Univ Fribourg, Dept Phys, CH-1700 Fribourg, Switzerland

[2] Univ Fribourg, Fribourg Ctr Nanomat, CH-1700 Fribourg, Switzerland

[3] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui, Peoples R China

[4] Univ Sci & Technol China, Dept Phys, Hefei 230026, Anhui, Peoples R China

来源：

PHYSICAL REVIEW LETTERS | 2008年 / 101卷 / 09期

基金：

瑞士国家科学基金会;

关键词：

D O I：

10.1103/PhysRevLett.101.097011

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We present far-infrared ellipsometric measurements of polycrystalline samples of the pnictide superconductor RFeAsO0.82F0.18 (R = Nd and Sm). We find evidence that the electronic properties are strongly anisotropic such that the optical spectra are dominated by the weakly conducting c-axis response similar to the cuprate high-temperature superconductors. We deduce an upper limit of the c-axis superconducting plasma frequency of omega(SC)(pl,c) <= 260 cm(-1) corresponding to a lower limit of the c-axis magnetic penetration of lambda(c) >= 6 mu m and lambda(c)/lambda(ab) >= 30 as compared to lambda(ab) = 185 nm from muon spin rotation [A. Drew et al., arXiv:0805.1042 [Phys. Rev. Lett. (to be published)]]. We also observe a gaplike suppression of the conductivity in the superconducting state with a shoulderlike feature at omega(SC)* approximate to 300 cm(-1) and spectral shape which is consistent with an unconventional order parameter with 2 Delta approximate to omega(SC)* approximate to 37 meV.

引用

页数：4

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