Identifying the gap structure with muons in the new superconductor La3Os

Superconductors that form in lower-symmetry crystal structures have the potential to exhibit unconventional behaviour, because there are less restrictions on the exact form of the order parameter. In both orthorhombic superconductors La3Co and La3Ni, electronic structure calculations indicate that spin fluctuations play a role in the enhancing the coupling strength. We propose to study a polycrystalline sample of La3Os, which is a new superconductor that forms in the same structure as La3(Co, Ni). Heat capacity data indicate that La3Os exhibits an unknown unconventional gap structure. We propose to use muons to study the mixed state and search for signatures of time-reversal symmetry breaking to identify the superconducting pairing state in La3Os.