Anisotropic spin fluctuations in CeCoIn5 Original Research Article

CeCoIn5 is an unconventional heavy fermion superconductor with a relatively large transition temperature View the MathML sourceTc=2.3K. NMR measurements of the spin lattice relaxation rate at the In(1) site reveal a significant anisotropy of the fluctuating hyperfine fields, which reverses below 30 K. These results suggest that two-dimensional fluctuations of the Ce 4f moments are relevant for the superconducting pairing.