Computational Search for Superconducting Chromium Oxides: A Multi-Stage Heuristic Pipeline Identifies a Stable Magnetically-Mediated Superconducting Basin in Oxygen-Deficient Cr₁₋δOδ with Dilute Transition-Metal Dopants
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2026
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| _version_ | 1866901956989026304 |
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| author | Fenning, Nicholas Brian |
| author_facet | Fenning, Nicholas Brian |
| contents | <p>We report the computational identification of a robust superconducting candidate basin in oxygen-deficient chromium oxides of approximate composition Cr₀.₇₇–0.⁸⁸ O₀.₁₂–0.₁₆ doped with 1–2% transition-metal or rare-earth substituents. Using a four-stage heuristic refinement pipeline — broad oxide brute-force search, motif-level precision refinement, micro-refinement, and per-dopant isolation — applied across 7,500 candidate compositions drawn from a search space of hundreds of thousands of evaluations, we find that this compositional basin consistently scores among the highest-ranked candidates across all refinement stages. The dominant predicted mechanism is magnetic/spin-fluctuation mediated superconductivity, not conventional phonon pairing: the electron-phonon coupling λ ≈ 0.43 yields a bare Allen-Dynes phonon Tc of approximately 1.3 K, while magnetic enhancement factors calibrated against analogous spin-fluctuation superconductors yield a corrected estimate of 2.6–10.3 K, with a central value near 5 K. Four transition-metal dopants (Ni, Co, Fe, Mn) and seven rare-earth dopants produce near-equivalent performance, with the compositional optimum tightly constrained to Cr ≈00.87, O ≈00.12, dopant ≈0.01–0.02. Literature review confirms that (i) CrO₂ carries experimentally verified spin-triplet supercurrents, (ii) Co, Ni, and Mn doping of Cr₂O₃ thin films produces room-temperature ferromagnetism, and (iii) oxygen-deficient Cr-rich compositions lie in a metallic conduction regime. No prior systematic superconductivity search in this composition window is found in the literature. DFT input files for the top 50 candidates are deposited alongside this preprint. Experimental verification via thin-film deposition or high-pressure synthesis is feasible with standard cryogenics laboratory equipment.</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_19062272 |
| institution | Zenodo |
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| publishDate | 2026 |
| publisher | Zenodo |
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| spellingShingle | Computational Search for Superconducting Chromium Oxides: A Multi-Stage Heuristic Pipeline Identifies a Stable Magnetically-Mediated Superconducting Basin in Oxygen-Deficient Cr₁₋δOδ with Dilute Transition-Metal Dopants Fenning, Nicholas Brian chromium oxide superconductivity oxygen-deficient oxide spin-fluctuation superconductivity magnetic mechanism computational materials discovery heuristic search Allen-Dynes equation electron-phonon coupling transition metal oxide Cr2O3 corundum structure dopant screening DFT validation VASP Quantum ESPRESSO magnetically mediated pairing iron pnictide analogy spin-triplet Stoner criterion oxide superconductor independent research AI-assisted discovery multi-stage refinement pipeline Eliashberg correction independent research <p>We report the computational identification of a robust superconducting candidate basin in oxygen-deficient chromium oxides of approximate composition Cr₀.₇₇–0.⁸⁸ O₀.₁₂–0.₁₆ doped with 1–2% transition-metal or rare-earth substituents. Using a four-stage heuristic refinement pipeline — broad oxide brute-force search, motif-level precision refinement, micro-refinement, and per-dopant isolation — applied across 7,500 candidate compositions drawn from a search space of hundreds of thousands of evaluations, we find that this compositional basin consistently scores among the highest-ranked candidates across all refinement stages. The dominant predicted mechanism is magnetic/spin-fluctuation mediated superconductivity, not conventional phonon pairing: the electron-phonon coupling λ ≈ 0.43 yields a bare Allen-Dynes phonon Tc of approximately 1.3 K, while magnetic enhancement factors calibrated against analogous spin-fluctuation superconductors yield a corrected estimate of 2.6–10.3 K, with a central value near 5 K. Four transition-metal dopants (Ni, Co, Fe, Mn) and seven rare-earth dopants produce near-equivalent performance, with the compositional optimum tightly constrained to Cr ≈00.87, O ≈00.12, dopant ≈0.01–0.02. Literature review confirms that (i) CrO₂ carries experimentally verified spin-triplet supercurrents, (ii) Co, Ni, and Mn doping of Cr₂O₃ thin films produces room-temperature ferromagnetism, and (iii) oxygen-deficient Cr-rich compositions lie in a metallic conduction regime. No prior systematic superconductivity search in this composition window is found in the literature. DFT input files for the top 50 candidates are deposited alongside this preprint. Experimental verification via thin-film deposition or high-pressure synthesis is feasible with standard cryogenics laboratory equipment.</p> |
| title | Computational Search for Superconducting Chromium Oxides: A Multi-Stage Heuristic Pipeline Identifies a Stable Magnetically-Mediated Superconducting Basin in Oxygen-Deficient Cr₁₋δOδ with Dilute Transition-Metal Dopants |
| topic | chromium oxide superconductivity oxygen-deficient oxide spin-fluctuation superconductivity magnetic mechanism computational materials discovery heuristic search Allen-Dynes equation electron-phonon coupling transition metal oxide Cr2O3 corundum structure dopant screening DFT validation VASP Quantum ESPRESSO magnetically mediated pairing iron pnictide analogy spin-triplet Stoner criterion oxide superconductor independent research AI-assisted discovery multi-stage refinement pipeline Eliashberg correction independent research |
| url | https://doi.org/10.5281/zenodo.19062272 |