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arXiv · 2606.29470

Orbital-Selective Diagonal-Gap Test of Pairing in La$_3$Ni$_2$O$_7$

Yu-Bo Liu·Zhi-Yan Shao·Zhiming Pan·Chen Lu·Fan Yang
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Abstract

Recent angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) measurements on bilayer nickelate La$_3$Ni$_2$O$_7$ reveal a nearly isotropic, nodeless superconducting gap. We show that these single-particle spectra provide a symmetry-enforced test of the pairing nature. Mirror symmetry forces the hybridization between $d_{z^2}$ and $d_{x^2-y^2}$ orbitals to vanish along the Brillouin-zone (BZ) diagonal. Consequently, the gaps on the diagonal portions of the $\alpha/\beta$ and $\gamma$ Fermi pockets separately probe the intrinsic pairing strengths of the $d_{x^2-y^2}$ and $d_{z^2}$ sectors. A pairing state with pure or dominant intrinsic $d_{z^2}$-orbital pairing component produces nodes or near-nodes on the BZ diagonal of the $\alpha/\beta$ pockets and is thus challenged by ARPES and STM, whereas the pairing state with dominant intrinsic $d_{x^2-y^2}$-orbital pairing component has a nearly isotropic, nodeless gap on all pockets which well fits ARPES and STM data. The dominant $d_{x^2-y^2}$-orbital pairing is compatible with Hund's-rule-driven pairing mechanisms.

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Yu-Bo Liu, Zhi-Yan Shao, Zhiming Pan, Chen Lu, Fan Yang. 2026-06-28. Orbital-Selective Diagonal-Gap Test of Pairing in La$_3$Ni$_2$O$_7$. https://arxiv.org/abs/2606.29470

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