27Al NMR studies in CeNiAl4:: a dense Kondo system

Al-27 nuclear magnetic resonance (NMR) studies were performed in CeNiAl4, a fluctuating valence system with Kondo temperature T*approximate to 99 K and showing heavy fermion behavior at low temperature. The temperature dependence of the lineshape and the spin lattice relaxation rate (1/T-1) were measured in the range 75-300 K. The effect of Ce-4f electron moment on the lineshape was found to be less pronounced. Moreover, the contribution of the 4f electron spin fluctuation to the Al nuclear spin-lattice relaxation process was also found to be less effective in this temperature range compared to that of the contact interaction of the conduction electrons. This suggests a faster spin fluctuation rate of the Ce-4f electron compared to the NMR time scale. (C) 2001 Elsevier Science B.V. All rights reserved.