Microscopic evidence of the FFLO state in CeCoIn5 probed by NMR study

An anomalous temperature dependence of 115In‐NMR spectrum is observed in the newly‐discovered high field and low temperature superconducting phase of CeCoIn5. The anomalies near the upper limit of H C 2 are attributed to spatially‐distributed local density of states of quasiparticles. From a simulation with the phenomenological model for the sinusoidally‐modulated superconducting order parameter, the present NMR study provides a microscopic evidence that the Fulde‐Ferrell‐Larkin‐Ovchinnikov (FFLO) state is realized at the high field phase in CeCoIn5. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)