Ga-69,Ga-71-NMR study of the low-energy excitations in NdGa2

We report the results of Ga-69- and Ga-71-NMR measurements on NdGa2 at temp eratures between 0.1 and 3 K and in applied magnetic fields between zero an d T4 kOe. NdGa2 orders antiferromagnetically below 9.5 K and undergoes seve ral metamagnetic transitions in external magnetic fields. In zero applied m agnetic field and below 1 K the temperature dependence of the spin-lattice relaxation rate T-1(-1)(T) shows a large linear-in-T term, about two orders of magnitude higher than for the reference compound LaGa2. This strong enh ancement confirms the presence of low-energy excitations in the antiferroma gnetic phase of NdGa2 as was previously indicated by specific heat data. Ab ove 1 K, T-1(-1) (T) is dominated by art exponential term, which we associa te with excitations between the lowest energy levels of the f-electron syst em. The separation of these energy levels is determined by exchange, crysta l-field and Zeeman interactions.