Probing the superconducting ground state of noncentrosymmetric superconductors using muon spectroscopy: A case of Re-based compounds*

Noncentrosymmetric superconductors (NCSs) with broken inversion symmetry has a direct influence on the superconducting properties of the system. In particular, NCSs with α-manganese structure has attracted much attention recently, after the discovery of time reversal symmetry breaking (TRSB) in all the members of the Re₆X (X = Ti, Hf, Zr) family [1,2]. Its persistence and the independent nature of the particular transition metal, points to a key role played by Re. To test such a hypothesis, and to ascertain the possible relevance of the noncentrosymmetric structure to TRSB in Re-based NCSs, we proceeded with a twofold study. On one hand, we studied the Re₆X family of compounds using muon spectroscopy, whereas, on the other hand we also studied the NbOs₂ compound, which doesn’t contain Re as the primary element and adopts similar α-Mn structure with superconducting transition temperature T_c = 2.7 K [3]. The results of muon spin relaxation/rotation measurements strongly suggests that the local electronic structure of Re is crucial for understanding the TRSB superconducting state in Re₆X.
(1) D.Singh et al., PRB 96,180501(R) (2017). (2) D.Singh et al.,PRB 97,100505(R) (2018) (3) D.Singh et al., PRB 99,014516 (2019).