Optical properties and electronic correlations in La$_3$Ni$_2$O$_7$ bilayer nickelates under high pressure

Fuente: arXiv
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Main Authors: Geisler, Benjamin, Fanfarillo, Laura, Hamlin, James J., Stewart, Gregory R., Hennig, Richard G., Hirschfeld, P. J.
Format: Preprint
Published: 2024
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author Geisler, Benjamin
Fanfarillo, Laura
Hamlin, James J.
Stewart, Gregory R.
Hennig, Richard G.
Hirschfeld, P. J.
author_facet Geisler, Benjamin
Fanfarillo, Laura
Hamlin, James J.
Stewart, Gregory R.
Hennig, Richard G.
Hirschfeld, P. J.
contents We explore the optical properties of La3Ni2O7 bilayer nickelates by using density functional theory including a Coulomb repulsion term. Convincing agreement with recent experimental ambient-pressure spectra is achieved for U=3eV, which permits tracing the microscopic origin of the characteristic features. Simultaneous consistency with angle-resolved photoemission spectroscopy and x-ray diffraction suggests the notion of rather moderate electronic correlations in this novel high-Tc superconductor. Oxygen vacancies form predominantly at the inner apical sites and renormalize the optical spectrum quantitatively, while the released electrons are largely accommodated by a defect state. We show that the structural transition occurring under high pressure coincides with a significant enhancement of the Drude weight and a reduction of the out-of-plane interband contribution that act as a fingerprint of the emerging hole pocket. We further calculate the optical spectra for various possible magnetic phases including spin-density waves and discuss the results in the context of experiment. Finally, we investigate the role of the 2-2 versus 1-3 layer stacking and compare the bilayer nickelate to La4Ni3O10, La3Ni2O6, and NdNiO2, unveiling general trends in the optical spectrum as a function of the formal Ni valence in Ruddlesden-Popper versus reduced Ruddlesden-Popper nickelates.
format Preprint
id arxiv_https___arxiv_org_abs_2401_04258
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Optical properties and electronic correlations in La$_3$Ni$_2$O$_7$ bilayer nickelates under high pressure
Geisler, Benjamin
Fanfarillo, Laura
Hamlin, James J.
Stewart, Gregory R.
Hennig, Richard G.
Hirschfeld, P. J.
Superconductivity
Materials Science
We explore the optical properties of La3Ni2O7 bilayer nickelates by using density functional theory including a Coulomb repulsion term. Convincing agreement with recent experimental ambient-pressure spectra is achieved for U=3eV, which permits tracing the microscopic origin of the characteristic features. Simultaneous consistency with angle-resolved photoemission spectroscopy and x-ray diffraction suggests the notion of rather moderate electronic correlations in this novel high-Tc superconductor. Oxygen vacancies form predominantly at the inner apical sites and renormalize the optical spectrum quantitatively, while the released electrons are largely accommodated by a defect state. We show that the structural transition occurring under high pressure coincides with a significant enhancement of the Drude weight and a reduction of the out-of-plane interband contribution that act as a fingerprint of the emerging hole pocket. We further calculate the optical spectra for various possible magnetic phases including spin-density waves and discuss the results in the context of experiment. Finally, we investigate the role of the 2-2 versus 1-3 layer stacking and compare the bilayer nickelate to La4Ni3O10, La3Ni2O6, and NdNiO2, unveiling general trends in the optical spectrum as a function of the formal Ni valence in Ruddlesden-Popper versus reduced Ruddlesden-Popper nickelates.
title Optical properties and electronic correlations in La$_3$Ni$_2$O$_7$ bilayer nickelates under high pressure
topic Superconductivity
Materials Science
url https://arxiv.org/abs/2401.04258