We report a comparative study on the crystal structure and physical properties of two high-entropy alloys (HEAs), ${\mathrm{Hf}}_{10}{\mathrm{Mo}}_{25}{\mathrm{W}}_{10}{\mathrm{Re}}_{35}{\mathrm{Ru}}_{20}$ and ${\mathrm{Ta}}_{10}{\mathrm{Mo}}_{25}{\mathrm{W}}_{10}{\mathrm{Re}}_{35}{\mathrm{Ru}}_{20}$. Despite a 10% difference in chemical composition, the former crystallizes in the noncentrosymmetric cubic $\alpha \text{−}\mathrm{Mn}$ structure while the latter adopts the centrosymmetric tetragonal $\sigma$-type structure. For both HEAs, bulk superconductivity is discovered and their specific heat jumps can be well described by a modified BCS model, consistent with a fully gapped state. In the normal state, the resistivity exhibits a temperature-independent or weakly insulating behavior, consistent with the presence of strong disorder scattering. Through comparison with isostructural HEA superconductors, we show that the selection between the $\alpha$-Mn and $\sigma$-type phases correlates with the valence electron concentration of HEAs and atomic size difference of constituent elements.

Close

PrevNext

View figure in article

• Crystal structure
• Electron-phonon coupling
• Phase transitions
• Superconductivity
• Disordered alloys
• High-entropy alloys
• Multi-principal element alloys
• Superconductors