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Complete superconducting phase diagram and flux pinning mechanisms in the yttrium-containing high-entropy alloy YNbTiZrHf

Rafał Idczak1, Wojciech Nowak1,2,*, and Adam Pikul2

  • *Contact author: wojciech.nowak@uwr.edu.pl
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Phys. Rev. B 114, 094507 – Published 11 August, 2026

DOI: https://doi.org/10.1103/k1yr-t59z

Abstract

We report on the synthesis and characterization of an yttrium-containing high-entropy alloy (HEA) superconductor obtained from a nominal YNbTiZrHf composition. Structural analysis reveals a body-centered-cubic matrix with minor yttrium-rich hexagonal precipitates. Comprehensive measurements of electrical resistivity, magnetization, ac magnetic susceptibility, and specific heat confirm bulk type-II superconductivity with a transition temperature Tc≈6.1K, a critical current density Jc≈45kA/cm2, and an upper critical field μ0Hc2=12.5T, exceeding the Pauli limit due to strong spin-orbit scattering. The superconducting phase diagram, constructed from Jc(T), Jc(μ0H), and μ0H(T) data, is reported for a HEA superconductor. Flux pinning analysis indicates dominant surface pinning with a secondary point contribution, while collective pinning theory reveals a crossover from δTc-type to δl-type pinning with increasing field. The estimated depairing current density Jd≈21MA/cm2, which is more than 2 orders of magnitude higher than the experimental Jc, suggests significant potential for performance enhancement through microstructural optimization.

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Phys. Rev. B 114, 094507– Published 11 August, 2026
  • Received 21 November 2025
  • Revised 27 April 2026
  • Accepted 10 July 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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