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5 linked papers

1 linked paper

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Using first-principles density functional theory calculations, we systematically investigate the electron-doping effects of tetravalent element substitution in double-layer Ruddlesden-Popper nickelate La₃Ni₂O₇ thin films. Unlike cuprates, cerium (Ce) doping is found to be inefficient in introducing electron carriers into low-energy bands, whereas zirconium (Zr), hafnium (Hf), and thorium (Th) serve as effective electron dopants. These elemental substitutions significantly enhance the interlayer hopping integral t⊥ between Ni-dz² orbitals, potentially strengthening the interlayer superexchange coupling J⊥ and thereby potentially increasing the superconducting transition temperature Tc. Using the constrained random phase approximation to evaluate interaction parameters, we find that electron doping increases the occupancy of low-energy orbitals (including Ni-dx²-y² and dz² along with their hybridized oxygen orbitals) and alters the electron filling ratio between in-plane and interlayer orbitals. Structural analysis reveals that differences in dopant ionic radii cause variations in Ni–O bond lengths, with Zr and Hf inducing lattice contraction and Th exhibiting the strongest doping effect. These results indicate that Zr, Hf, and Th are promising candidates for achieving electron doping in La₃Ni₂O₇, offering a new avenue to clarify the ongoing debate over the electron pairing mechanism in this system.

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9 linked papers

By combining density functional theory and dynamical mean-field theory, the evolution of the electronic structure, magnetism, and correlation effects in the infinite-layer nickelate LaNiO₂ under electron and hole doping is investigated. The results reveal that, due to the presence of rare-earth 5d states, the self-doping effect of the Ni-d_{x²-y²} band exhibits significant asymmetry: hole doping strongly suppresses self-doping, whereas electron doping, while enlarging the rare-earth 5d electron pocket, does not effectively hole-dope the Ni-d_{x²-y²} band. This difference directly impacts the magnetic response—hole doping rapidly suppresses antiferromagnetic order, while electron doping maintains the antiferromagnetic state as the ground state. Despite these disparities, the electronic correlations in both doping regimes are dominated by the Ni-d_{x²-y²} orbital, suggesting that a single-band description may be applicable in both electron- and hole-doped regions.