Study of the FFLO State and the Anomalous Magnetic Order in CeCoIn5

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To improve our understanding of how the exotic superconductivity and magnetism can interact in CeCoIn5, we measured 115In NMR and demonstrate the emergence of a spatially distributed normal quasiparticle region in the HL-phase in parallel field. The field evolution of the paramagnetic magnetization and low energy quasiparticle DOS can be described well by the order parameter associated with the nodal plane formation via the FFLO second order phase transition. The evolution of NMR spectra with respect to angle between external field and a-axis reveasl that the magnetic structure changes from the spatially-uniform to the spatially-modulated one. The exotic FFLO phase is suppressed with increasing the angle, and disappears for beyond 20 degree.Our results provide strong evidence for the formation of the FFLO state via the second order phase transition and coexistence ot the static magnetic order and FFLO state.