Time reversal symmetry breaking in noncentrosymmetric superconductor Re₆Ti

Superconductors with noncentrosymmetric crystal structure are of considerable interest due to their possible realization of unconventional superconductivity. The lack of inversion symmetry in the lattices of these materials has significant implications on the symmetry of their superconducting state. The direct consequence of the broken inversion symmetry was first recognized in the noncentrosymmetric superconductor (NCS) CePt₃Si. It shows upper critical field exceeding Pauli limiting field, indicating unconventional behaviour. In an NCS, the lack of inversion symmetry introduces a Rashba-type antisymmetric spin-orbit coupling (ASOC), which results in the splitting of spin-up and spin-down conduction electron energy bands. This leads to exhibit an unconventional ground-state, which consists of an admixture of spin-singlet and spin-triplet Cooper pairs. Nevertheless, it has yet to be conclusively verified in any material to this date. The superconducting state of the noncentrosymmetric superconductor Re₆Ti (T_c = 6 K) using muon-spin rotation/relaxation (μSR) technique has been investigated