Superconducting Properties and Absence of Time Reversal Symmetry Breaking in the Noncentrosymmetric Superconducting Compounds Ta x Re1 – x (0.1 ≤ x ≤ 0.25)* *Supported by the National Key R&D Program of China (Grant No. 2018YFA0704300), the National Natural Science Foundation of China (Grant Nos. U1732162, 11974061, 11704047, U1832147 and 11674054), and the Strategic Priority Research Program (B) of the

Abstract

Unconventional superconductivity, in particular, in noncentrosymmetric systems, has been a long-sought topic in condensed matter physics. Recently, Re-based superconductors have attracted great attention owing to the potential time-reversal symmetry breaking in their superconducting states. We report the superconducting properties of noncentrosymmetric compounds Ta x Re1 – x with 0.1 ≤ x ≤ 0.25, and find that the superconducting transition temperature reaches a maximum of ∼8 K at the optimal level x = 0.15. Nevertheless, muon-spin rotation and relaxation measurements reveal no time-reversal symmetry breaking existing in its superconducting state, which is in sharp contrast to both centrosymmetric Re metal and many other noncentrosymmetric Re-based superconductors.