Superconductivity in the Medium-Entropy Alloy TiVNbTa with a Body-Centered Cubic Structure

Abstract

Here, we report the TiVNbTa medium-entropy alloy (MEA) superconductor with the mixed 3d–5d elements synthesized by an arc-melting method. The TiVNbTa material has a body-centered cubic structure with the cell parameter a = 3.2547(3) Å. The superconducting properties of TiVNbTa were studied by resistivity, magnetic susceptibility, and specific heat measurements. The experimental results show that the bulk superconducting phase transition temperature of TiVNbTa is about 4.65 K, and the upper and lower critical fields are 49.3(4) mT and 5.9(5) T, respectively, which indicates that TiVNbTa is a type-II superconductor. First-principles calculations show that the d electrons of Ti, V, Nb, and Ta atoms play a significant role near the Fermi level. The results show that TiVNbTa is a traditional s-wave superconductor (ΔCel/γTc = 1.60(2), λep = 0.76(3)).