27Al and 65Cu NMR study in UCu5Al

We have studied the microscopic properties of the tetragonal UCu5Al Kondo compound by 27Al and 63,65Cu NMR in the paramagnetic state. NMR and susceptibility measurements performed on the powdered sample, but oriented along the applied field, showed chi(parallel) > chi(perpendicular). Plots of K(parallel)(T) against chi(parallel)(T) at temperatures T > or = 100 K yield the transferred hyperfine fields of +5.9 kOe/micron(B) for 27Al nuclei, and +5.3 and -7.0 kOe/micron(B) for 65Cu nuclei in crystallographically inequivalent Cu(2) and Cu(1) sites, respectively. The Knight shift vs. susceptibility plots for T < 100 K exhibit a deviation from the linear behaviour (absolute values of shifts become smaller than expected). We attribute this finding to the crystalline electric field effect in similar way as it was reported for several Ce-based compounds. The random distribution of the Al and Cu(2) atoms in the crystal lattice we consider as a reason of an unusual broadening of the NMR spectra, particularly at low temperatures.