MuSR study of high spin-orbital coupling non-symmorphic superconducting compounds

Nonsymmorphic space groups, featuring screw axes and glide planes, provide a platform for realizing novel topological phases, including topological semimetals and unconventional superconductors. These symmetries constrain electronic band structures, leading to degeneracies and influencing superconducting pairing. Recent observations of time-reversal symmetry breaking (TRSB) in nonsymmorphic Dirac semimetals and the interplay between nonsymmorphic symmetry and strong spin-orbit coupling (SOC) in potential TRSB superconductors highlight this potential. To further explore these connections, we propose a detailed investigation of the newly discovered superconductors W7X3 (X = Ir, Os), which crystallize in the nonsymmorphic tetragonal space group P42/mnm and contain high-Z elements suggesting strong SOC. Initial band structure calculations indicate topological semimetallic behavior with Dirac-type crossings and potential flat bands for W7Os3, suggesting a non-trivial topology. Thus, W7X3 are promising candidates for exhibiting unconventional superconductivity and TRSB. This study aims to elucidate the fundamental roles of topological properties, SOC, and nonsymmorphic crystal structure in the emergence of TRSB and unconventional superconductivity.