27Al-NQR study in BaNiSn3-type CeCuAl3

We have firstly observed 27Al-NQR signal in CeCuAl3, which is assigned to the Al(2) site, one of the two crystallographic sites of Al (Al(1) and Al(2)). The NQR spectrum in the paramagnetic region is composed of two kinds of Al(2) signals associated with the different environments. One comes from Al(2) in the regular atomic configuration and the other is attributed to Al(2) affected by the neighboring site-disorder between Cu and Al(1) sites. NQR measurement were performed on sample containing less than 5% site-disorder which is the best one we obtained. The start of the spectral broadening as well as the critical divergence of the nuclear spin-lattice relaxation rate 1/T1 indicate that TN ≅ 3.3 K. The broad spectrum suggests an incommensurate modulation in the antiferromagnetic state. 1/T1 in the paramagnetic state is well explained in terms of the dynamics of Ce 4f localized moment through RKKY and the cf exchange interactions.