Sensitive dependence of pairing symmetry on Ni-eg crystal field splitting in the nickelate superconductor La3Ni2O7

Chengliang Xia; Hongquan Liu; Shengjie Zhou; Hanghui Chen

doi:10.1038/s41467-025-56206-0

Sensitive dependence of pairing symmetry on Ni-e_g crystal field splitting in the nickelate superconductor La₃Ni₂O₇

Nat Commun. 2025 Jan 26;16(1):1054. doi: 10.1038/s41467-025-56206-0.

Authors

Chengliang Xia^#¹, Hongquan Liu^#^{1

2}, Shengjie Zhou¹, Hanghui Chen^{3

4}

Affiliations

¹ NYU-ECNU Institute of Physics, NYU Shanghai, Shanghai, China.
² Department of Physics, Brown University, Providence, RI, USA.
³ NYU-ECNU Institute of Physics, NYU Shanghai, Shanghai, China. hanghui.chen@nyu.edu.
⁴ Department of Physics, New York University, New York, NY, USA. hanghui.chen@nyu.edu.

^# Contributed equally.

PMID: 39865112
DOI: 10.1038/s41467-025-56206-0

Abstract

The discovery of high-temperature superconductivity in La₃Ni₂O₇ under pressure has drawn great attention. However, consensus has not been reached on its pairing symmetry in theory. By combining density-functional-theory (DFT), maximally-localized-Wannier-function, and linearized gap equation with random-phase-approximation, we find that the pairing symmetry of La₃Ni₂O₇ is d_xy, if its DFT band structure is accurately reproduced by a downfolded bilayer two-orbital model. More importantly, we reveal that the pairing symmetry of La₃Ni₂O₇ sensitively depends on the crystal field splitting between two Ni-e_g orbitals. A slight increase in Ni-e_g crystal field splitting alters the pairing symmetry from d_xy to s_±. Such a transition is associated with the change in inverse Fermi velocity and susceptibility, while the shape of Fermi surface remains almost unchanged. Our work highlights the sensitive dependence of pairing symmetry on low-energy electronic structures in multi-orbital superconductors, which calls for care in the downfolding procedure when one calculates their pairing symmetry.