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arXiv · 0812.1670

Insular superconductivity in Co-doped iron pnictide CaFe$_{1-x}$Co$_x$AsF

S. Takeshita·R. Kadono·M. Hiraishi·M. Miyazaki·A. Koda·S. Matsuishi·H. Hosono
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Abstract

The presence of macroscopic phase separation between the superconducting and magnetic phases in \cfcaf is demonstrated by muon spin rotation (muSR) measurements conducted across their phase boundaries (x=0.05-0.15). The magnetic phase tends to retain the high transition temperature (T_m > T_c), while Co-doping induces strong randomness. The volumetric fraction of superconducting phase is nearly proportional to the Co content $x$ with constant superfluid density. These observations suggest the formation of superconducting "islands" (or domains) associated with Co ions in the Fe$_2$As$_2$ layers, indicating a very short coherence length.

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S. Takeshita, R. Kadono, M. Hiraishi, M. Miyazaki, A. Koda, S. Matsuishi, H. Hosono. 2009-06-15. Insular superconductivity in Co-doped iron pnictide CaFe$_{1-x}$Co$_x$AsF. https://doi.org/10.1103/physrevlett.103.027002

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