Interplay of Chemical Disorder, Vortex Pinning, and Electron Correlations in the Mechanically Robust Medium-Entropy Alloy Superconductor Nb0.45Ta0.25Ti0.15Hf0.15
Abstract
Medium and high-entropy alloys have emerged as a promising class of superconducting materials because their intrinsic chemical disorder can simultaneously enhance mechanical robustness and modify superconducting properties. Here, we present a combined experimental and first-principles investigation of the structural, superconducting, electronic, and local lattice-distortion characteristics of the mechanically robust medium-entropy alloy Nb0.45Ta0.25Ti0.15Hf0.15. The material shows type-II superconductivity with a transition temperature TConset ≈ 7.8 K. A high critical current density of Jc = 0.48 × 106 A/cm2 is observed, and this is attributed to strong vortex pinning at grain boundaries. Specific-heat analysis indicates a strong electron-phonon coupling (λ = 1.07) with a large isotropic s-wave superconducting gap. Density functional theory calculations explicitly model the intrinsic chemical disorder, predict a stable body-centered cubic phase. These calculations further reveal a metallic electronic structure with substantial Ti- and Ta-derived states at the Fermi level. Additionally, our results quantify a pronounced disorder-induced local lattice distortion (Δd = 0.086 A), providing a microscopic basis for the experimentally observed enhanced vortex-pinning landscape. Remarkably, the alloy also exhibits an unusually large Kadowaki-Woods ratio, placing it close to the heavy-fermion regime and indicating enhanced electronic correlations beyond conventional alloy superconductors. Our results demonstrate that entropy-engineered chemical disorder can stabilize robust superconductivity, promote strong flux pinning, and induce correlated electronic behavior, establishing refractory medium-entropy alloys as a promising platform for next-generation superconducting materials.
Related
- Intriguing topological superconductor phases in long-range extended Kitaev models: an interplay between sub-lattices and power-law interaction
- Interplay of electric field and electronic correlations in pairing competition in bilayer nickelates
- Interplay of chemical structure and magnetic order coupling at the interface between Cr2O3 and Fe3O4 in hybrid nanocomposites
- Interplay of Composition, Crystallinity, and Chemical Structure in CoHCF and NiHCF Thin Films Prepared at Different Temperatures
- Interplay of disorder and phonons in two-dimensional transport
BibTeX
@misc{chourasia2026interplay,
title = {{Interplay of Chemical Disorder, Vortex Pinning, and Electron Correlations in the Mechanically Robust Medium-Entropy Alloy Superconductor $\textNb_0.45\textTa_0.25\textTi_0.15\textHf_0.15$}},
author = {Pooja Chourasia and Samiul Sk and Nikita Sharma and B. Vignolle and Abhishek Sarkar and Olivier Toulemonde and Sanjoy Mahatha and S. K. Panda and Sourav Marik},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32449},
eprint = {2610.32449},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32449},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Interplay of Chemical Disorder, Vortex Pinning, and Electron Correlations in the Mechanically Robust Medium-Entropy Alloy Superconductor Nb_0.45Ta_0.25Ti_0.15Hf_0.15
AU - Pooja Chourasia
AU - Samiul Sk
AU - Nikita Sharma
AU - B. Vignolle
AU - Abhishek Sarkar
AU - Olivier Toulemonde
AU - Sanjoy Mahatha
AU - S. K. Panda
AU - Sourav Marik
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32449
UR - https://arxiv.org/abs/2610.32449
AB - Medium and high-entropy alloys have emerged as a promising class of superconducting materials because their intrinsic chemical disorder can simultaneously enhance mechanical robustness and modify superconducting properties. Here, we present a combined experimental and first-principles investigation of the structural, superconducting, electronic, and local lattice-distortion characteristics of the mechanically robust medium-entropy alloy Nb_0.45Ta_0.25Ti_0.15Hf_0.15. The material shows type-II superconductivity with a transition temperature T_C^onset ≈ 7.8 K. A high critical current density of J_c = 0.48 × 10^6 A/cm^2 is observed, and this is attributed to strong vortex pinning at grain boundaries. Specific-heat analysis indicates a strong electron-phonon coupling (λ = 1.07) with a large isotropic s-wave superconducting gap. Density functional theory calculations explicitly model the intrinsic chemical disorder, predict a stable body-centered cubic phase. These calculations further reveal a metallic electronic structure with substantial Ti- and Ta-derived states at the Fermi level. Additionally, our results quantify a pronounced disorder-induced local lattice distortion (Δd = 0.086 A), providing a microscopic basis for the experimentally observed enhanced vortex-pinning landscape. Remarkably, the alloy also exhibits an unusually large Kadowaki-Woods ratio, placing it close to the heavy-fermion regime and indicating enhanced electronic correlations beyond conventional alloy superconductors. Our results demonstrate that entropy-engineered chemical disorder can stabilize robust superconductivity, promote strong flux pinning, and induce correlated electronic behavior, establishing refractory medium-entropy alloys as a promising platform for next-generation superconducting materials.
ER -