Electronic Reconstruction across the Tilt-Free Transition in La3Ni2O7
Abstract
The emergence of high-Tc superconductivity in pressurized La3Ni2O7 is intimately linked to a structural transition that suppresses the tilts of the NiO6 octahedra, yet its impact on the electronic structure remains poorly understood. Here, we probe the electronic response across this tilt-free transition at Tst≃ 544 K using broadband infrared-to-visible reflectivity at ambient pressure, covering photon energies from 15 meV to 3.2 eV. We observe a pronounced redistribution of spectral weight over an exceptionally broad energy range, with spectral weight transferred from excitations between 1 and 3 eV toward low-energy excitations below 1 eV. Most strikingly, two low-energy interband excitations progressively converge and merge upon entering the tilt-free phase, revealing a substantial reconstruction of the finite-energy electronic structure. These changes point to a reconstruction of the bilayer Ni 3dz2-derived electronic states, whose interlayer coupling is central to proposed mechanisms of superconductivity in La3Ni2O7. Our results establish the tilt-free transition as a direct route to reorganizing the electronic degrees of freedom implicated in high-Tc superconductivity and provide an ambient-pressure reference for the electronic structure of the superconducting state.
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BibTeX
@misc{kong2026electronic,
title = {{Electronic Reconstruction across the Tilt-Free Transition in La$_3$Ni$_2$O$_7$}},
author = {Mengjie Kong and Gergely Németh and Yingpeng Yu and Bosen Wang and Jianping Sun and Jinguang Cheng and Ferenc Borondics and Bastien Michon},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.40139},
eprint = {2609.40139},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.40139},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Electronic Reconstruction across the Tilt-Free Transition in La_3Ni_2O_7
AU - Mengjie Kong
AU - Gergely Németh
AU - Yingpeng Yu
AU - Bosen Wang
AU - Jianping Sun
AU - Jinguang Cheng
AU - Ferenc Borondics
AU - Bastien Michon
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.40139
UR - https://arxiv.org/abs/2609.40139
AB - The emergence of high-T_c superconductivity in pressurized La_3Ni_2O_7 is intimately linked to a structural transition that suppresses the tilts of the NiO_6 octahedra, yet its impact on the electronic structure remains poorly understood. Here, we probe the electronic response across this tilt-free transition at T_st≃ 544 K using broadband infrared-to-visible reflectivity at ambient pressure, covering photon energies from 15 meV to 3.2 eV. We observe a pronounced redistribution of spectral weight over an exceptionally broad energy range, with spectral weight transferred from excitations between 1 and 3 eV toward low-energy excitations below 1 eV. Most strikingly, two low-energy interband excitations progressively converge and merge upon entering the tilt-free phase, revealing a substantial reconstruction of the finite-energy electronic structure. These changes point to a reconstruction of the bilayer Ni 3d_z^2-derived electronic states, whose interlayer coupling is central to proposed mechanisms of superconductivity in La_3Ni_2O_7. Our results establish the tilt-free transition as a direct route to reorganizing the electronic degrees of freedom implicated in high-T_c superconductivity and provide an ambient-pressure reference for the electronic structure of the superconducting state.
ER -