Superconducting state in the non-centrosymmetric Mg9.3Ir19B16.7 and Mg10.5Ir19B17.1 revealed by NMR
Abstract
We report 11B NMR measurements in non-centrosymmetric superconductors Mg9.3Ir19B16.7 (Tc=5.8 K) and Mg10.5Ir19B17.1 (Tc=4.8 K). The spin lattice relaxation rate and the Knight shift indicate that the Cooper pairs are predominantly in the spin-singlet state with an isotropic gap. However, Mg10.5Ir19B17.1 is found to have more defects and the spin susceptibility remains finite even in the zero-temperature limit. We interpret this result as that the defects enhance the spin-orbit coupling and bring about more spin-triplet component.
0