11B NMR relaxation in superconductors: YRuB2 and LuRuB2 Original Research Article

To investigate the electronic states in YRuB2 and LuRuB2, we have carried out 11B NMR measurements. In the normal state, the spin-lattice relaxation rates 1/T1ʹs in these compounds are proportional to the temperature T. 1/T1ʹs show a small coherence peak just below the superconducting transition temperature Tc and decrease exponentially well below Tc. YRuB2 and LuRuB2 are found to be BCS superconductors with the energy gap 2Δ(0)=3.52 kBTc.