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Landscape of coexisting excitonic states in the insulating single-layer cuprates and nickelates

Authors :
Lane, Christopher
Zhu, Jian-Xin
Source :
Phys. Rev. B 101, 155135 (2020)
Publication Year :
2020

Abstract

We present an $\textit{ab initio}$ study of the excitonic states of a prototypical high-temperature superconductor La$_2$CuO$_4$ and compare them to the isostructural single-layer nickelate La$_2$NiO$_4$. Key difference in the low-energy electronic structure leads to very different excitonic behavior. Excitons in La$_2$CuO$_4$ are delocalized and can freely move in the CuO$_2$ plane without disturbing the antiferromagnetic order. In contrast, in La$_2$NiO$_4$ we find the low-lying excitonic states to be extremely localized, producing a nearly flat dispersion. The theoretically obtained excitonic dispersion and behavior are in excellent agreement with RIXS observations. To classify the excitons we project the electron-hole coupling onto each atomic site including the full manifold of atomic orbitals. We find the excitons to be composed of a linear combination of exciton classes, including Mott-Hubbard, $d-d$, and charge-transfer. The implication of these excitations to the high-$T_c$ pairing mechanism is also discussed.<br />Comment: 11 pages, 4 figures

Details

Database :
arXiv
Journal :
Phys. Rev. B 101, 155135 (2020)
Publication Type :
Report
Accession number :
edsarx.2003.00098
Document Type :
Working Paper
Full Text :
https://doi.org/10.1103/PhysRevB.101.155135