The bilayer nickelate superconductor La3Ni2O7 undergoes a density wave transition near 150 K that has attracted intensive scrutiny, yet its microscopic origin remains elusive. Here we report polarization-resolved electronic Raman scattering measurements on high-quality single crystals of La3Ni2O7. Below 150\,K, we observe a pronounced, symmetry-dependent redistribution of spectral weight in B1g and B2g channels, consistent with the formation of spin-density-wave (SDW) gaps. Quantitative analysis reveals momentum-selective SDW gap amplitudes, with intermediate-to-strong coupling near X/Y points of the Brillouin zone and weaker coupling along the diagonal direction, indicating an unconventional SDW driven by anisotropic electronic correlations. Our results establish the electronic character of the SDW in La3Ni2O7, and provide a microscopic foundation for understanding the emergence of high-temperature superconductivity under pressure in nickelates.
@article{arxiv.2602.07998,
title = {Anisotropic Electronic Correlations in the Spin Density Wave State of La$_3$Ni$_2$O$_7$},
author = {Ge He and Jun Shen and Shiyu Xie and Haotian Zhang and Mengwu Huo and Jun Shu and Deyuan Hu and Xiaoxiang Zhou and Yanmin Zhang and Lei Qin and Liangxin Qiao and Hengjie Liu and Chuansheng Hu and Xijie Dong and Dengjing Wang and Jun Liu and Wei Hu and Jie Yuan and Yajun Yan and Zeming Qi and Kui Jin and Zengyi Du and Meng Wang and Donglai Feng},
journal= {arXiv preprint arXiv:2602.07998},
year = {2026}
}