Contrasting Momentum-Selective Spin-Density-Wave Gaps in Bilayer and Trilayer Nickelates

Jun Shu; Jun Shen; Xiaoxiang Zhou; Yinghao Zhu; Qingsong Wang; Dengjing Wang; Weihong He; Jie Yuan; Kui Jin; Dawei Shen; Congcong Le; Jun Zhao; Zengyi Du; Ge He; Donglai Feng

arXiv · 2602.02174

Contrasting Momentum-Selective Spin-Density-Wave Gaps in Bilayer and Trilayer Nickelates

Jun Shu·Jun Shen·Xiaoxiang Zhou·Yinghao Zhu·Qingsong Wang·Dengjing Wang·Weihong He·Jie Yuan·Kui Jin·Dawei Shen·Congcong Le·Jun Zhao·Zengyi Du·Ge He·Donglai Feng

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Abstract

Resolving where the density-wave gap opens in momentum space is essential for identifying the microscopic origin of the instability in layered nickelates. Using polarization-resolved electronic Raman scattering, we map the momentum selectivity of the spin-density-wave (SDW) gap in trilayer La4Ni3O10. We observe a SDW-induced redistribution of spectral weight on both the $\alpha$ pocket at the Brillouin-zone centre and a portion of the $\beta$ pocket near the zone boundary, characterized by gap energies of approximately 55~meV. In contrast, no comparable spectral weight suppression is observed along the diagonal region of $\beta$ pockets, implying little or no gap opening. This gap topology contrasts sharply with that in La3Ni2O7, where anisotropic SDW gaps open solely on the $\beta$ pocket. Our results establish a distinct momentum-space gap topology between bilayer and trilayer nickelates, placing new constraints on the ordering wave vector and the mechanism of the density-wave instability relevant to superconductivity.

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Jun Shu, Jun Shen, Xiaoxiang Zhou, Yinghao Zhu, Qingsong Wang, Dengjing Wang, Weihong He, Jie Yuan, Kui Jin, Dawei Shen, Congcong Le, Jun Zhao, Zengyi Du, Ge He, Donglai Feng. 2026-02-02. Contrasting Momentum-Selective Spin-Density-Wave Gaps in Bilayer and Trilayer Nickelates. https://arxiv.org/abs/2602.02174

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