Electronic behavior of the doped GdBaSrCu 3- x M x O 7- δ ( M = Zn, Ni) superconductor by density functional theory

Abstract This study employs first-principles density functional theory (DFT) to investigate the electronic behavior of the GdBaSrCu 3 O 7- δ high-temperature superconductor after zinc (Zn) and nickel (Ni) doping at the copper (Cu)-site. The novelty of this study lies in correlating dopant-induced modifications in O(2 p ) and transition-metal d -states with changes in elastic properties and Debye temperature, providing microscopic insight into the suppression of superconductivity. The structural, elastic and electronic properties of the samples were calculated and analyzed using CASTEP code, contributing to sustainable materials research and clean energy technology. The optimized lattice parameters, elastic constants, and Debye temperature are in good agreement with available experimental data. Electronic structure calculations reveal that Zn and Ni doping increases the d -electron density at the Fermi level, leading to enhanced d -electron repulsion ( U ) within the CuO 2 planes. This increased repulsion correlates with the suppression of superconductivity. Notably, the greater sum of 3 d electron densities of states for Zn and Cu compared to Ni and Cu suggests a more significant detrimental impact of Zn doping on the superconducting properties. These findings provide valuable insights into the mechanisms governing the suppression of superconductivity in doped cuprates, ultimately supporting sustainable technological advancement.