Pressure-induced anomalous magnetism and unconventional superconductivity in CeRhIn5:: 115In-NQR study under pressure -: art. no. 220507

We report In-115 nuclear-quadrupole-resonance (NQR) measurements of the pressure(P)-induced superconductor CeRhIn5 in the antiferromagnetic (AF) and superconducting (SC) states. In the AF region, the internal field H-int at the In site is substantially reduced from H-int= 1.75 kOe at P=0 to 0.39 kOe at P=1.23 GPa, while the Neel temperature slightly changes with increasing P. This suggests that either the size in the ordered moment M-Q(P) or the angle theta(P) between the direction of M-Q(P) and the tetragonal c axis is extrapolated to zero at P*=1.6+/-0.1 GPa at which a bulk SC transition is no longer emergent. In the SC state at P=2.1 GPa, the nuclear spin-lattice relaxation rate (115)(1/T-1) has revealed a T-3 dependence without the coherence peak just below T-c, giving evidence for the unconventional superconductivity. The dimensionality of the magnetic fluctuations in the normal state is also discussed.