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Texture in the Superconducting Order Parameter of CeCoIn_5 Revealed by Nuclear Magnetic Resonance

K. Kakuyanagi·M. Saito·K. Kumagai·S. Takashina·M. Nohara·H. Takagi·Y. Matsuda
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Abstract

We present a ^{115}In NMR study of the quasi two-dimensional heavy-fermion superconductor CeCoIn_5 believed to host a Fulde-Ferrel-Larkin-Ovchinnkov (FFLO) state. In the vicinity of the upper critical field and with a magnetic field applied parallel to the ab-plane, the NMR spectrum exhibits a dramatic change below T*(H) which well coincides with the position of reported anomalies in specific heat and ultrasound velocity. We argue that our results provide the first microscopic evidence for the occurrence of a spatially modulated superconducting order parameter expected in a FFLO state. The NMR spectrum also implies an anomalous electronic structure of vortex cores.

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K. Kakuyanagi, M. Saito, K. Kumagai, S. Takashina, M. Nohara, H. Takagi, Y. Matsuda. 2004-05-28. Texture in the Superconducting Order Parameter of CeCoIn_5 Revealed by Nuclear Magnetic Resonance. https://doi.org/10.1103/physrevlett.94.047602

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