Layer-resolved impurity states reveal competing pairing mechanisms in trilayer nickelate superconductor La4Ni3O10

Abstract

Trilayer Ruddlesden-Popper nickelate superconductor La4Ni3O10 has generated considerable interest due to its unconventional superconductivity and complex electronic structure. Notably, La4Ni3O10 features a mixed Ni valence state and an asymmetric trilayer configuration, leading to distinct quasiparticle distributions and local density of states (LDOS) between the inner and outer NiO2 planes. In this work, we investigate impurity-induced states in La4Ni3O10 using a two-orbital model combined with T-matrix formalism, focusing on the contrasting roles of intra- and interlayer pairing channels. Our self-consistent mean-field analysis reveals that interlayer pairing results in partially gapless Fermi surfaces, with unpaired quasiparticles concentrated in the outer layers and a pronounced low-energy LDOS. We demonstrate that impurity effects vary significantly depending on both the pairing symmetry and impurity location: interlayer-dominant pairing produces sharp resonance states when impurities are in the inner layer, whereas impurities in the outer layer lead to in-gap enhancements without sharp resonances; in contrast, intralayer-dominant pairing generally yields increased in-gap LDOS without sharp impurity resonances, regardless of impurity position. These findings suggest that single-impurity spectroscopy can serve as a powerful probe to distinguish between competing superconducting pairing mechanisms in trilayer nickelates and highlight the rich physics arising from their multilayer structure.

Source-reported materials — not catalogue approval

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