Ga-NMR study of the low-energy excitations in

: We report the results of 69 Ga- and 71 Ga-NMR measurements on NdGa 2 at temperatures between 0.1 and and in applied magnetic fields between zero and 74 kOe. NdGa 2 orders antiferromagnetically below and undergoes several metamagnetic transitions in external magnetic fields. In zero applied magnetic field and below the temperature dependence of the spin-lattice relaxation rate T1 -1 ( T ) shows a large linear-in- T term, about two orders of magnitude higher than for the reference compound LaGa 2 . This strong enhancement confirms the presence of low-energy excitations in the antiferromagnetic phase of NdGa 2 as was previously indicated by specific heat data. Above , T1 -1 ( T ) is dominated by an exponential term, which we associate with excitations between the lowest energy levels of the f -electron system. The separation of these energy levels is determined by exchange, crystal-field and Zeeman interactions.