Pressure-induced anomalous magnetism and unconventional superconductivity in (formula presented) (formula presented)-NQR study under pressure

We report (formula presented) nuclear-quadrupole-resonance (NQR) measurements of the pressure (formula presented)-induced superconductor (formula presented) in the antiferromagnetic (AF) and superconducting (SC) states. In the AF region, the internal field (formula presented) at the In site is substantially reduced from (formula presented) at (formula presented) to 0.39 kOe at (formula presented) while the Néel temperature slightly changes with increasing P. This suggests that either the size in the ordered moment (formula presented) or the angle (formula presented) between the direction of (formula presented) and the tetragonal c axis is extrapolated to zero at (formula presented) at which a bulk SC transition is no longer emergent. In the SC state at (formula presented) the nuclear spin-lattice relaxation rate (formula presented) has revealed a (formula presented) dependence without the coherence peak just below (formula presented) giving evidence for the unconventional superconductivity. The dimensionality of the magnetic fluctuations in the normal state is also discussed.