Probing the unconventional normal and superconducting states of a heavy d-electron superconductor

In unconventional superconductors, the superconductivity often emerges from a normal state with strong electronic correlations, as well being in close proximity to magnetic order or other novel phases. Superconductivity emerging from a ferromagnetic normal state is particularly rare. Recently, evidence has been found for a weakly ferromagnetic normal state in a binary superconductor which has also shown hints of unconventional superconductivity, as well as strong electronic correlations. Therefore, we propose to perform muon-spin relaxation/rotation measurements in both the normal and superconducting states of this material. Measurements in the normal state will be used to probe this weak ferromagnetism, whereby muon-spin relaxation is especially suitable for determining whether the ferromagnetism is homogeneous, or if there is phase separation. These results can also reveal the temperature evolution of the magnetism, as well as information about the dynamics. Transverse field measurements will be used to probe the superconducting state, so as to extract the temperature dependence of the penetration depth, which will be fitted with models for the superconducting gap. Knowledge of the gap structure can provide key evidence as to the nature of the superconducting state and whether or not it is conventional.