Related papers: On the oxygen $p$ states in superconducting nickel…
Superconductivity in nickelates apparently takes place in two different Ni oxidation regimes, namely either for infinite-layer-type compounds close to Ni$^{+}$, or for Ruddlesden-Popper materials close to Ni$^{2+}$. The reduced…
The discovery of superconductivity in square-planar low valence nickelates has ignited a vigorous debate regarding their essential electronic properties: Do these materials have appreciable oxygen charge-transfer character akin to the…
High-T$_c$ superconductivity has recently been discovered in Ruddlesden-Popper phase nickelates under pressure, where the low-energy electronic structure is dominated by Ni $d_{x^2 - y^2}$ and $d_{z^2}$ orbitals. However, the respective…
Unusual metallic states involving breakdown of the standard Fermi-liquid picture of long-lived quasiparticles in well-defined band states emerge at low temperatures near correlation-driven Mott transitions. Prominent examples are…
The metal-insulator transitions and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding of these materials remains elusive.…
Three low-valence layered nickelates with general formula La$_3$Ni$_2$O$_{7-\delta}$ ($\delta$=0.0, 0.5, 1) are studied by ab initio techniques. Both the insulating and metallic limits are analyzed, together with the compound at the Mott…
The synthesis of high-quality Ruddlesden-Popper (RP) nickelates remains challenging due to variations in oxygen content and the prevalence of intergrown RP phases. Precisely controlling the stoichiometry and characterizing the resulting…
We theoretically investigate the unconventional superconductivity in the newly discovered infinite-layer nickelates Nd$_{1-x}$Sr$_{x}$NiO$_{2}$ based on a two-band model. By analyzing the transport experiments, we propose that the doped…
The discovery of superconductivity in infinite-layer nickelates has added a new family of materials to the fascinating growing class of unconventional superconductors. By incorporating the strongly correlated multi-orbital nature of the…
The occurrence of superconductivity in proximity to various strongly correlated phases of matter has drawn extensive focus on their normal state properties, to develop an understanding of the state from which superconductivity emerges. The…
Experiments have shown that the families of cuprate superconductors that have the largest transition temperature at optimal doping also have the largest oxygen hole content at that doping. They have also shown that a large charge-transfer…
We theoretically study quasi-two-dimensional nickel compounds, where the nickel ions assume Ni$^{2+}$ $d^8$ valence state and feature a low-spin $S=0$ ground state quasidegenerate with $S=1$ ionic excitations. Such a level structure is…
Superconductivity in the cuprates exhibits many unusual features. We study the two-dimensional Hubbard model with plaquette dynamical mean-field theory to address these unusual features and relate them to other normal-state phenomena, such…
We propose that the superconductivity recently observed in Nd$_{0.8}$Sr$_{0.2}$NiO$_2$ with critical temperature in the range $9$ K to $15$ K results from the same charge carriers and the same mechanism that we have proposed give rise to…
Topotactic transition is a structural phase change in a matrix crystal lattice mediated by the ordered loss/gain and rearrangement of atoms, leading to unusual coordination environments and metal atoms with rare valent states. As early as…
High-temperature superconductivity in bilayer nickelate La$_3$Ni$_2$O$_7$ under pressure has attracted significant interest in condensed matter physics. While early samples exhibited limited superconducting volume fractions, Pr substitution…
The new family of superconducting nickelates centered around La$_{3}$Ni$_{2}$O$_{7}$ possesses attractive features, such as the high transition temperature and the presence of an antiferromagnetic ground state at ambient pressure,…
The properties of AMO3 perovskite oxides, where M is a 3d transition metal, depend strongly on the level of covalency between the metal d and oxygen p orbitals. With their complex spin orders and metal-insulator transition, rare-earth…
Dynamical mean field theory calculations are used to show that for late transition-metal-oxides a critical variable for the Mott/charge-transfer transition is the number of d-electrons, which is determined by charge transfer from oxygen…
We report the observation of superstructures associated with the oxygen 2p-states in two prototypical manganites using x-ray diffraction at the oxygen K-edge. We determine the nature of the orderings and discuss our picture with respect to…