Superconductivity in the high-entropy alloy (NbTa)0.67(MoHfW)0.33

Abstract

Structural and physical properties of the high-entropy alloy (NbTa)0.67(MoHfW)0.33 were studied by x-ray powder diffraction, energy dispersive x-ray spectroscopy, magnetization, electrical resistivity, and specific heat measurements. The experimental results were supported by theoretical calculations using two complementary approaches for electronic structure calculations: the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA) and projector augmented wave (PAW) within the density functional theory. It was found that the alloy forms with a cubic, body-centered structure (space group Im3¯m, W-type structure) with a lattice parameter a=3.287(1) Å and a random (but microscopically homogeneous) distribution of the constituent elements. At high temperature the alloy exhibits simple metallic behavior, while at low temperature it becomes a type-II superconductor with the critical temperature Tc≈4.3 K and the upper critical field μ0Hc2≈1.45 T. The electron-phonon coupling constant calculated from the PAW data, λel−phth−PAW=0.63, is in perfect agreement with the experimental results.

Source-reported materials — not catalogue approval

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