Appearance of anisotropic non s-wave superconductivity above the critical pressure of antiferromagnetic CeRhln5 -: 115In nuclear quadrupole resonance study

We have carried out In-115 nuclear quadrupole resonance (NQR) measurements in CeRhIn5. At ambient pressure, CeRhIn5 undergoes all antiferromagnet ic AF phase transition at T-N = 3.8 K. The In-115 NQR spectrum has shown the appearance of a small internal field in the direction perpendicular to the tetragonal c-axis. With application of a hydrostatic pressure, the AF state is suppressed and the superconductivity appears just above the critical pressure (P = 17 kbar). The nuclear spin lattice relaxation rate 1/T-1 of In-115 measured at P = 27 kbar indicates the occurrence of the superconductivity in the nearly AF region. In the superconducting state, 1/T-1 has no Hebel-Slichter coherence peak just below T-c of 2 K anti has a pou-er law T-dependence (T-3) down to 300 mK. This is consistent with anisotropic superconductivity. with line nodes in the superconducting energy gap: non-s-wave superconductivity occurs in CeRhIn5.