Effect of doping on the electronic structure, orbital-dependent renormalizations, and magnetic correlations in bilayer La3Ni2O7

Abstract

Using the density functional theory plus dynamical mean-field theory (DFT+DMFT) approach, we study the effects of electronic correlations and doping on the normal state electronic structure of the double-layer nickelate superconductor La3Ni2O7 (LNO) under pressure. In agreement with experiments, we obtain significant orbital-dependent quasiparticle renormalizations of the Ni x2−y2 and 3z2−r2 bands, accompanied by incoherence (bad metal behavior) of the 3z2−r2 states, caused by the proximity of the Ni 3d states to orbital-dependent localization. Our results demonstrate a sensitive, nonmonotonic dependence of m*/m on doping, with a remarkable, by about 20%, increase for the Ni x2−y2 orbitals upon electron doping x∼0.2 (per Ni ion), implying a significant enhancement of orbital-dependent correlations with oxygen deficiency in LNO. We observe a reconstruction of the low-energy electronic structure of LNO upon doping above x∼−0.3 and 0.2. It is associated with the Lifshitz transition, with a crossover to a self-doping regime characterized by partial occupation of the La 5d bands (upon an electron doping x>0.2). Our analysis of the static magnetic susceptibility χ(q) obtained within DFT+DMFT suggests the possible formation of the spin and charge (or bond) density wave stripes, implying strong spin and charge correlations in LNO. We show that this behavior is associated with the suppression of the Néel G-type antiferromagnetic ordering of the Ni2+ ions upon hole doping. Interestingly, upon a moderate electron doping of the Ni2.5+ ions (e.g., with oxygen deficiency), we find a significant enhancement of the strength of in-plane spin and charge fluctuations. We note a close resemblance of our results to those for the bilayer Hubbard model, which shows the boosting of superconductivity as one of the two electron bands approaches the Lifshitz transition (e.g., upon doping). Our results suggest that spin and charge stripe fluctuations, effectively tuned by doping, play a key role in pressure-driven superconductivity in LNO.

Source-reported materials — not catalogue approval

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