101Ru NQR Study in Superconducting CeRu2

We present measurements of the NQR spectrum and the nuclear spin lattice relaxation rate, 1/ T 1 , of 101 Ru in superconducting CeRu 2 from 1.9 K to 10 K. From the NQR spectrum, the electric quadrupole interaction parameters were determined to be ν Q =13.2 MHz and η=0.1/ T 1 varies in proportion to temperature in the normal state, and has the Hebel-Slichter coherence peak just below the superconducting transition temperature, T C , of 6.2 K, and decreases exponentially at low temperatures with the energy gap of 2Δ=4.0 k B T c . 101 Ru NQR study indicates that CeRu 2 is an s-wave and strong-coupling superconductor.