NMR study of a FFLO state of CeCoIn5in a perpendicular and a parallel field

We study the NMR of newly-discovered superconducting state of CeCoIn5 in a perpendicular field (H ⊥ ab) as well as in a parallel field (H || ab), Upon entering the new SC state at high field and low temperature region, NMR spectra change dramatically below T(HC) in the case of H ⊥ ab as well as H || ab. A well-separated spectrum for H ≥4.7 T persists down to the lowest temperature, which indicates the appearance of a nodal plane structure as expected for Fulde-Ferrell-Larkin-Ovchinnkov (FFLO) state. We find the critical field HFFLO⊥ separating the FFLO and the BCS state lies in a very narrow range between 4.65 T and 4.70 T below TC(H).