  Superconducting high-entropy alloys (HEAs) are a newly burgeoning field of
unconventional superconductors and raise intriguing questions about the
presence of superconductivity in highly disordered systems, which lack regular
phonon modes. In our study, we have synthesized and investigated the
superconducting characteristics of two new transition elements based HEAs
Re$_{0.35} $Os$_{0.35} $Mo$_{0.08} $W$_{0.10} $Zr$_{0.12}$ (ReOMWZ)
crystallizing in noncentrosymmetric $\alpha$-Mn structure, and Ru$_{0.35}
$Os$_{0.35} $Mo$_{0.10} $W$_{0.10} $Zr$_{0.10}$ (RuOMWZ) crystallizing
hexagonal closed-packed structure (hcp). Transition metal-based hexagonal hcp
HEA is rare and highly desirable for practical applications due to their high
hardness. Bulk magnetization, resistivity, and specific heat measurements
confirmed bulk type-II superconductivity in both alloys. Specific heat analysis
up to the measured low-temperature range suffices for a BCS explanation.
Comparable upper critical fields with the Pauli paramagnetic limit suggest the
possibility of unconventional superconductivity in both HEAs.
