The discovery of superconductivity in Ruddlesden-Popper nickelates has established a new frontier in the study of high-temperature superconductors. However, the underlying pairing mechanism and its relationship to the material's electronic and magnetic ground states remain elusive. Since unconventional superconductivity often emerges from a complex interplay of magnetic correlations, elucidating the magnetic ground state of the nickelates at ambient pressure is crucial for understanding the emergence of superconductivity under high pressure. Here, we combine high-resolution angle-resolved photoemission spectroscopy with tight-binding model simulation to investigate the electronic structure of the representative trilayer Ruddlesden-Popper nickelate La4Ni3O10. We provide the first experimental evidence of band splitting induced by interlayer coupling and further resolve the momentum-dependent density wave gap structures along all the Fermi surfaces. Our findings identify the mirror-selective Fermi surface nesting as the origin of the interlayer antiferromagnetic spin density wave and demonstrate the dominant role of Ni-3dz2 orbitals in the low-energy physics of La4Ni3O10. These results provide a fundamental framework for understanding the magnetic interactions and high-temperature superconductivity mechanism in the Ruddlesden-Popper nickelate family.
@article{arxiv.2601.22608,
title = {Electronic Origin of Density Wave Orders in a Trilayer Nickelate},
author = {Jiangang Yang and Jun Zhan and Taimin Miao and Mengwu Huo and Qichen Xu and Yinghao Li and Yuyang Xie and Bo Liang and Neng Cai and Hao Chen and Wenpei Zhu and Mingkai Xu and Shenjin Zhang and Fengfeng Zhang and Feng Yang and Zhimin Wang and Qinjun Peng and Hanqing Mao and Xintong Li and Zhihai Zhu and Guodong Liu and Zuyan Xu and Jiangping Hu and Xianxin Wu and Meng Wang and Lin Zhao and X. J. Zhou},
journal= {arXiv preprint arXiv:2601.22608},
year = {2026}
}