Abstract
The discovery of superconductivity in thin films (∼10 nm) of infinite-layer hole-doped NdNiO2 has invigorated the field of high temperature superconductivity research, reviving the debate over contrasting views that nickelates that are isostructural with cuprates are either 1) sisters of the high temperature superconductors, or 2) that differences between nickel and copper at equal band filling should be the focus of attention. Each viewpoint has its merits, and each has its limitations, suggesting that such a simple picture must be superseded by a more holistic comparison of the two classes. Several recent studies have begun this generalization, raising a number of questions without suggesting any consensus. In this paper, we organize the findings of the electronic structures of n-layered NiO2 materials (n = 1 to ∞) to outline (ir)regularities and to make comparisons with cuprates, with the hope that important directions of future research will emerge.
Highlights
After much synthesis and characterization of low-valence layered nickelates over three decades [1,2,3,4,5,6,7], superconductivity was observed [8] in hole-doped RNiO2 with Tc exhibiting a dome-like dependence [12, 13] being maximal (10–15 K) near 20% doping. This series of discoveries in RNiO2 materials marked the beginning of a new, nickel age of superconductivity [14, 15] launching a plethora of experimental [16,17,18,19,20,21,22] and theoretical [23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43] work
We focus on the electronic structure of layered nickelates, Electronic Structure of Layered Nickelates confining ourselves to materials with the basic infinite-layer structure: n square planar NiO2 layers each separated by an R3+ ion without the apical oxygen ion(s) that are common in most cuprates and nickelates
From density functional theory (DFT) calculations, the charge-transfer energy of Nd6Ni5O12 is ∼ 4.0 eV. This reduced energy compared to the undoped infinite-layer material means that the Ni-3d states are not as close in energy to the Nd-5d states, consistent with the presence of a pre-peak in the oxygen K-edge
Summary
After much synthesis and characterization of low-valence layered nickelates over three decades [1,2,3,4,5,6,7], superconductivity was observed [8] in hole-doped RNiO2 (initially for rare earth R Nd, later for R La [9, 10] and Pr [11]) with Tc exhibiting a dome-like dependence [12, 13] being maximal (10–15 K) near 20% doping. RNiO2 materials are the n ∞ member of a larger series of layered nickelates with chemical formula (RO2)−[R(NiO2)n]+
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
