Specific heat of the non-centrosymmetric superconductor Re3W

The alloys of non-centrosymmetric superconductor, Re₃W, which were reported to have an α-Mn structure P. Greenfield and P. A. Beck, J. Metals, N. Y. 8, 265 (1959)] with T_c=9K, are prepared by arc melting. The values of ac susceptibility and the low-temperature specific heat of these alloys are measured. It is found that there are two superconducting phases coexisting in the samples with T_c1≈9K and T_c2≈7K, which are both non-centrosymmetric in structure as reported previously. By analysing the specific heat data measured in various magnetic fields down to a temperature of 1.8K, we find that the absence of the inversion symmetry does not lead to an obvious deviation from an s$-wave pairing symmetry in Re₃W.