Al-27 nuclear magnetic resonance studies of CeAuAl3

We report Al-27 Nuclear Magnetic Resonance studies of CeAuAl3 and LaAuAl3 a t frequencies between 1.30 and 76.91 MHz and at temperatures from 45 mK up to 320 K. CeAuAl3 is a new heavy-electron compound which orders antiferroma gnetically at 1.32 K. For the two inequivalent Al sites of CeAuAl3, the tra nsferred hyperfine couplings H-hf = 1.91 kOe/mu(B) and H-hf = 2.40 kOe/mu(B ) are relatively small. compared to those in other Ce compounds. The nuclea r quadrupolar coupling constants e(2)qQ/h are 2.9 MHz and 7.8 MHz, respecti vely. We suggest that the magnetic structure of the ordered state below 1.3 2 K is of a simple spiral type with the ordered Ce moments arranged ferroma gnetically within the.(ab) planes of the tetragonal crystal lattice. Based on this magnetic structure we estimate a 25% reduction of the Ce moments, m ost likely due to Kondo screening. At high temperatures, in the paramagneti c state of CeAuAl3, the spin-lattice relaxation rate T-1(-1) is dominated b y the fluctuations of the localised Ce moments. At 20 K, T-1(-1) is 96 s(-1 ), more than two orders of magnitude larger than for the reference compound LaAuAl3. For temperatures lower than 20 K T-1(-1) decreases as a function of (T/H) and below 1 K, displays a linear-in-T behaviour, strongly enhanced compared to the reference compound LaAuAl3.