Ga NMR/NQR study in UGa₃

Microscopic magnetic properties of a uraniun intermetallic compound, UGa₃ (T_N = 67 K), have been investigated by the ⁶⁹Ga and ⁷¹Ga NMR/NQR measurements. We found a drastic temperature (T-) dependence of the NQR spectrum near T_N, in which a single ⁶⁹Ga NQR line of 19.8 MHz in the paramagnetic state rapidly vanishes at 70 K and a double peak appears at 17.2 and 16.55 MHz between 63 and 70 K. This result is significantly different from the case of the usual antiferromagnetic ordering, and suggests a transient modification of the electric field gradient at the Ga sites. The Ga nuclear spin-lattice relaxation rate T₁^-1 in the paramagnetic state shows local character for spin fluctuations of 5f-electrons rather than 5f-itinerant behavior.