Highly Uniform Magnetic and Electronic Environment in Non-Centrosymmetric Superconductor LaRhGe$_3$

We report the results of $^{139}$La NMR measurements in the non-centrosymmetric superconductor LaRhGe$_3$. This material crystallizes in a tetragonal structure without inversion symmetry and exhibits type-I superconductivity below 385 mK. We observed remarkably sharp NMR signals, indicating that the magnetic and electronic properties of the sample are extremely uniform in LaRhGe$_3$ despite the complex crystal structure. Our NMR results indicate that LaRhGe$_3$ is a weakly correlated semimetal in the normal state.