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The interplay of disorder, electronic correlations, and superconducting fluctuations in vanadium-titanium and niobium-titanium alloys is investigated using the coherent potential approximation (CPA) and dynamical mean-field theory (DMFT). For V-Ti alloys [1], the superconducting transition temperature $T_c$, estimated with the McMillan formula, shows a maximum at a Ti concentration near 0.33 for $U$ between 2 and 3 eV, in agreement with the experimentally observed $T_c$ increase of about 20%. For niobium and Nb$_{0.44}$Ti$_{0.56}$ in the bcc phase up to 250 GPa [2], significant topological changes in the Fermi surface and a weakening of correlations are found with increasing pressure. The normal state remains a Fermi liquid with well-defined quasiparticles. These results provide insight into the electronic states near the Fermi level relevant for the robust superconductivity of Ti-doped niobium under compression and highlight the need for further experimental studies. A connection is established between disorder-induced modifications of the electronic structure and superconducting properties, offering a framework for understanding robust superconductivity under varying disorder and pressure conditions.
[1] D. Jones, A. Östlin, A. Weh, F. Beiuseanu, U. Eckern, L. Vitos, L. Chioncel, Phys. Rev. B 109, 165107 (2024)
[2] D. Jones, A. Östlin, A. Chmeruk, F. Beiuseanu, U. Eckern, L. Vitos, L. Chioncel, Phys. Rev. B 111, 165152 (2025)
