Combined Experimental and Ab Initio Study of Sc Doping in MgB ₂ : Decoupling Electronic and Microstructural Effects on Superconductivity

In this study we revealed the effect of scandium doping on the electronic and superconducting properties of the MgB₂ compound. Calculations demonstrate that Sc substitutes for Mg atoms, acting as an electron donor. Mg substitution diminishes the density of states in the σ-band and attenuates the electron-phonon coupling, thereby elucidating the reduction in critical temperature. Simultaneously, Sc-induced microstructural defects serve as effective pinning centers, thereby improving the critical current density. The established separation of electronic and microstructural effects allows for the targeted modification of MgB₂ properties.