Interplay between Zhang-Rice singlets and high-spin states in a model for doped NiO${}_2$ planes

Abstract

Superconductivity found in doped NdNiO${}_2$ is puzzling as two local symmetries of doped NiO${}_2$ layers compete, with presumably far-reaching implications for the involved mechanism: a cuprate-like regime with Zhang-Rice singlets {\cblue is replaced by local triplet states at realistic values of charge-transfer energy, which would suggest a rather different superconductivity scenario from high-$T_c$ cuprates}. We address this competition by investigating Ni${}_4$O${}_8$ clusters with periodic boundary conditions in the parameter range relevant for the superconducting nickelates. With increasing value of charge-transfer energy we observe upon hole doping the expected crossover from the cuprate regime dominated by Zhang-Rice singlets to the local triplet states. We find that smaller charge-transfer energy $\Delta$ is able to drive this change of the ground state character when realistic values for nickel-oxygen repulsion $U_{dp}$ are taken into account. For large values of the charge-transfer energy, oxygen orbitals are less important than in superconducting cuprates as their spectral weight is found only at rather high excitation energies. However, a second Ni($3d$) orbital can easily become relevant, with either the $xy$ or the $3z^2-r^2$ orbitals contributing in addition to the $x^2-y^2$ orbital {\cblue to the formation of triplet states. In addition,} our result that $U_{dp}$ (acting between Ni and O) favors onsite triplets implies that correlation effects beyond purely onsite interactions should be taken into account when obtaining effective two-band models.

12 pages, 11 figures, under review

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Cited by in corpus (11)

• Dynamical Mean Field Studies of Infinite Layer Nickelates: Physics Results and Methodological Implications
• Low Valence Nickelates: Launching the Nickel Age of Superconductivity
• Role of Oxygen States in the Low Valence Nickelate La${}_4$Ni${}_3$O${}_8$
• Microscopic Theory of Superconducting Phase Diagram in Infinite-Layer Nickelates
• Dynamical structural instability and its implication on the physical properties of infinite-layer nickelates
• Screening in a two-band model for superconducting infinite-layer nickelate
• Excitons and trions in monolayer semiconductors with correlated electrons
• Assessing the correlated electronic structure of lanthanum nickelates
• Effective one-band models for the 1D cuprate Ba${}_{2-x}$Sr${}_x$CuO${}_{3+\delta }$
• Emergence and tunability of Fermi-pocket and electronic instabilities in layered Nickelates
• Character of Doped Holes in Nd${}_{1-x}$Sr${}_x$NiO${}_2$