Unconventional superconductivity and antiferromagnetic quantum phase transition in CeRhIn5: 115In-NQR study under pressure

We report on the pressure (P)-induced phase diagram of antiferromagnetism (AFM) and superconductivity (SC) which emerges at their border at zero magnetic field. The nuclear-quadrupole-resonance (NQR) measurements have revealed that AFM can take place in the superconducting state with T-c similar to 2.1 K at P = 2.05 GPa and the AFM quantum phase transition (QPT) occurs near P = 2.1 GPa. These results reveal the existence of the tetracritical point in the P-T phase diagram of AFM and SC in CeRnIn5. We also found the gapless nature in the uniformly coexisting phase of AFM and SC, indicating an intimate relationship between AFM and SC. (c) 2007 Elsevier B.V. All rights reserved.