Daily Overview: Today’s highlighted work focuses on the elucidation of the electronic structure of low-n-layer tetragonal nickelates and the theoretical exploration of new electron doping strategies. One study employs the DFT+DMFT method to reveal layer-resolved correlation effects: in the undoped system, the electronic correlation of Ni-d orbitals increases with the number of layers, and the inner NiO₂ planes are generally more strongly correlated than the outer ones. Through an electron compensation strategy involving Cl substitution in the spacer layer, the nominal Ni valence is tuned to a level comparable to that of optimal superconducting systems, and it is predicted that these systems can enter a strongly correlated metallic regime, providing a feasible pathway to transform low-layer nickelates into potential superconducting candidates. Another work proposes achieving disorder-free electron doping in nickelates via a heterostructure approach: by inserting a wide-bandgap insulating LaXO₃ layer, La₂NiO₄ accepts extra electrons supplied by (LaO)⁺ layers. Many-body theoretical calculations predict that the superconducting transition temperature can exceed 50 K and even reach as high as 127 K. This method is also applicable to systems such as La₃Ni₂O₇, opening a general scheme for the comprehensive exploration of the electron doping phase diagram of nickelates. arXiv submission processing window: 2026-07-10 00:00 to 2026-07-10 00:00 UTC.

1. Layer-resolved Electronic Structure and Correlation of Low-$n$ Square-planar Nickelates: A DFT+DMFT Prediction of Superconducting Candidates

Summary: This study employs density functional theory combined with dynamical mean-field theory (DFT+DMFT) to systematically analyze the layer-resolved electronic structure and correlation effects in low-n tetragonal nickelates. The results reveal that the electronic correlation strength of Ni-d orbitals in undoped systems increases with layer number, and that the inner NiO₂ planes consistently exhibit stronger correlations than the outer ones, a discrepancy originating from the inhomogeneous spatial charge distribution. For the n=2 and n=3 compounds, which are non-superconducting due to excessive hole doping, an electronic compensation strategy via Cl substitution at spacer-layer oxygen sites is proposed, and virtual crystal approximation simulations tune the nominal Ni valence to match that of the optimally superconducting n=6 system. Calculations demonstrate that Cl doping significantly enhances the Ni-d mass enhancement factor in the low-layer-number systems, driving them into the strongly correlated metallic regime while preserving the low-energy electronic structure. This work highlights the critical role of layer-resolved electronic correlations in the superconductivity mechanism and predicts that spacer-layer Cl doping is a viable pathway to convert low-n tetragonal nickelates into potential superconducting candidates.

2. Heterostructuring as Gateway to Electron Doping of Nickelate Superconductors

Summary: This study proposes a novel route to electron doping in nickelate superconductors through heterostructuring. First-principles calculations reveal that upon inserting wide-bandgap insulating layers of LaXO₃ (X = Al, Ga, Sc) into La₂NiO₄, the additional (LaO)⁺ layers act as electron donors, releasing carriers into the Ni-3d orbitals and thereby achieving disorder-free electron doping of Ruddlesden–Popper nickelates. This doping naturally places La₂NiO₄:La₂AlO₄ in the optimal regime for d_{x^2−y^2}-wave superconductivity, with many-body methods—including dynamical vertex approximation, fluctuation exchange, and dynamical cluster approximation—predicting a superconducting critical temperature exceeding 50 K and reaching as high as 127 K. The strategy circumvents the disorder typically introduced by conventional chemical doping, and is equally applicable to other nickelates such as La₃Ni₂O₇, offering a viable scheme for comprehensively mapping the electron-doping phase diagram of nickelates and extending the approach to other transition metal oxide systems.