Microwave Surface-Impedance Measurements of the Magnetic Penetration Depth in Single Crystal Ba1-xKxFe2As2 Superconductors: Evidence for a Disorder-Dependent Superfluid Density

被引:134
作者
Hashimoto, K. [1 ]
Shibauchi, T. [1 ]
Kasahara, S. [2 ,3 ]
Ikada, K. [1 ]
Tonegawa, S. [1 ]
Kato, T. [1 ]
Okazaki, R. [1 ]
van der Beek, C. J. [4 ]
Konczykowski, M. [4 ]
Takeya, H. [3 ]
Hirata, K. [3 ]
Terashima, T. [2 ]
Matsuda, Y. [1 ,4 ]
机构
[1] Kyoto Univ, Dept Phys, Sakyo Ku, Kyoto 6068502, Japan
[2] Kyoto Univ, Res Ctr Low Temp & Mat Sci, Kyoto 6068502, Japan
[3] Natl Inst Mat Sci, Tsukuba, Ibaraki 3050047, Japan
[4] Ecole Polytech, Solides Irradies Lab, F-91128 Palaiseau, France
关键词
LAYERED SUPERCONDUCTOR; GAPS; SPECTROSCOPY;
D O I
10.1103/PhysRevLett.102.207001
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
We report high-sensitivity microwave measurements of the in-plane penetration depth lambda(ab) and quasiparticle scattering rate 1/tau in several single crystals of the hole-doped Fe-based superconductor Ba1-xKxFe2As2 (x approximate to 0.55). While a power-law temperature dependence of lambda(ab) with a power similar to 2 is found in crystals with large 1/tau, we observe an exponential temperature dependence of the superfluid density consistent with the existence of fully opened two gaps in the cleanest crystal we studied. The difference may be a consequence of different levels of disorder inherent in the crystals. We also find a linear relation between the low-temperature scattering rate and the density of quasiparticles, which shows a clear contrast to the case of d-wave cuprate superconductors with nodes in the gap. These results demonstrate intrinsically nodeless order parameters in the Fe arsenides.
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页数:4
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