Effect of Annealing in Eutectic High-Entropy Alloy Superconductor NbScTiZr

• Published in: Journal of superconductivity and novel magnetism Vol. 37; no. 5-7; pp. 1059 - 1068
• Main Authors: Seki, Takeru, Arima, Hiroto, Kawasaki, Yuta, Nishizaki, Terukazu, Mizuguchi, Yoshikazu, Kitagawa, Jiro
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2024
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Development of new superconducting materials with exotic properties and mechanisms; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity; Critical current density; Eutectic structure; High-entropy alloy; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-023-06643-z

We investigated the impact of annealing on the structural characteristics and superconducting critical temperature ( T c ) of the eutectic high-entropy alloy (HEA) superconductor NbScTiZr. The HEA manifests an eutectic microstructure composed of body-centered cubic (bcc) and hexagonal close-packed phases. Both the lattice parameters of the bcc phase and grain size of the eutectic structure exhibited pronounced sensitivity to variations in annealing temperature. The observed dependence of the lattice parameter on annealing temperature supports the possibility that lattice strain occurs at lower annealing temperatures. The as-cast sample demonstrated superconductivity at T c of 7.9 K, which increased to 9 K after annealing at 800 ∘ C. However, when subjected to annealing at 1000 ∘ C, T c diminishes to 8.7 K. The annealing temperature dependence of T c cannot be comprehensively elucidated based solely on the electronic density of states at the Fermi level. It is plausible that the lattice strain may influence the annealing temperature dependence of T c . Our results for the critical current density J c reveal that the self-field J c of the as-cast NbScTiZr at 2 K exceeds 10 6 A/cm 2 .