Enhanced Superconducting Critical Parameters in a New High-Entropy Alloy Nb(0.34)Ti(0.33)Zr(0.14)Ta(0.11)Hf(0.08)

The structural and physical properties of the new titanium- and niobium-rich type-A high-entropy alloy (HEA) superconductor Nb [Formula: see text] Ti [Formula: see text] Zr [Formula: see text] Ta [Formula: see text] Hf [Formula: see text] (in at.%) were studied by X-ray powder diffraction, energy dispersive X-ray spectroscopy, magnetization, electrical resistivity, and specific heat measurements. In addition, electronic structure calculations were performed using two complementary methods: the Korringa–Kohn–Rostoker Coherent Potential Approximation (KKR-CPA) and the Projector Augmented Wave (PAW) within Density Functional Theory (DFT). The results obtained indicate that the alloy exhibits type II superconductivity with a critical temperature close to 7.5 K, an intermediate electron–phonon coupling, and an upper critical field of 12.2(1) T. This finding indicates that Nb [Formula: see text] Ti [Formula: see text] Zr [Formula: see text] Ta [Formula: see text] Hf [Formula: see text] has one of the highest upper critical fields among all known HEA superconductors.