In-NQR study of CeIn₃ under pressure

In order to investigate the evolution of magnetic properties when the ground state changes from magnetism to superconductivity, we have performed In-NQR measurements under hydrostatic pressure in heavy-fermion antiferromagnetic compound, CeIn₃. Peaks in the In-NQR spectra were shifted in the magnetically ordered state due to the appearance of the asymmetric parameter η, which enables us to determine the ordering temperature T_N, precisely. T_N in our measurement is in good agreement with that from the resistivity measurement. Nuclear spin-lattice relaxation rate 1/T₁ increases gradually upon cooling in the paramagnetic state at pressure (P) smaller than 15 kbar, whereas 1/T₁ shows slightly decreasing behavior with decreasing T above T_N at P>15 kbar. It is suggested that the magnetic property at T_N may change from the localized to itinerant regime around 15 kbar, above which the Kondo temperature T_K is higher than T_N.