NMR studies of Th2Zn17-type U2Cu8Al9 and Ce2Cu8Al9

In order to investigate the heavy fermion properties from a microscopic standpoint we have made Al-27 and Cu-63,Cu-65 NMR measurements on CeCu8Al9 and U2Cu8Al9 for 1.3-200 K, with special interest to comparison between the Ce and the U compound. The Al-27 relaxation rate 1/T-1 observed at 11 MHz (H = 1 T) in U2Cu8Al9 showed a sharp peak at 2 K, but the peak reduced rapidly with increasing resonance field and disappeared entirely at 5 T. The peak of 1/T-1 at 2 K, coinciding with a cusp-like peak observed in the AC susceptibility, is attributed to the spin-glass-like ordering at 2 K. In a high held of 5 T, 1/T-1 was nearly constant above 4 K but decreased gradually below 3 K. The relaxation rate for Al-27 in Ce2Cu8Al9 heavy fermion material showed a similar temperature dependence as observed for 5 T in U2Cu8Al9. (C) 1998 Elsevier Science B.V. All rights reserved.