RU-101 NQR STUDY OF ANTIFERROMAGNETIC SUPERCONDUCTOR URU2SI2

We have carried out Ru-101 NQR measurement of URu2Si2 in zero magnetic field in the temperature (T) range from 0.16 to 130 K. The electric q uadrupole interaction parameters of Ru-101 were determined to be nu(Q) = 5.72 MHz and eta = 0 at 1.3 K. Although URu2Si2 is in the antiferro magnetic (AF) state below 17.5 K, no broadening of NQR line was observ ed, indicating that transferred hyperfine field from U moments is canc elled at Ru site. The nuclear spin-lattice relaxation rate (1/T-1) dec reases drastically below 17.5 K associated with AF ordering. In the su perconducting state, 1/T-1 has no coherence peak just below T-C = 1.2 K, and decreases in proportion to T-3 With no deviation down to 0.2 K, which shows the existence of line nodes in the superconducting energy gap.