Unveiling the nature superconducting gap structure in disordered simple cubic Au0.17Sb0.83

Antimony (Sb), being a semimetal, shows superconductivity when substituted with 17.5% Au and stabilized in a simple cubic structure in high-temperature and high-pressure synthesis. The normal state heat capacity analysis suggests a strong electron-phonon coupling with a nominal density of states of value 0.58 states per eV per f.u. The superconducting heat capacity deviates from the BCS single-gap s-wave model. A single-gap α-model fit yields Δ = 2.02 kBTc, exceeding the weak-coupling BCS value of 1.76 kBTc. A two-gap isotropic s + s-wave model also fits the data, with gap ratios of 0.41:0.59 and magnitudes Δ₁ = 2.08 kBTc and Δ₂ = 1.96 kBTc. However, the similarity between gap values and their contributions causes significant overlap with the α-model, making it difficult to confirm multigap behavior. Further, there has been no investigation that probes the pairing mechanism in this kind of binary disordered compounds with a simple cubic structure. Therefore, we propose to perform muon spin rotation (μSR) experiments on this sample that could provide valuable insights into the underlying superconducting gap structure and help verify the presence of multigap superconductivity in it.