Daily Overview: This post sorts papers by relevance to nickelate superconductors. Summaries are AI-generated and may contain errors. arXiv submission processing window: times are unavailable (UTC).

1. High-energy electronic excitations in La3Ni2O7 by time-resolved optical spectroscopy

  • Relevance Score: 5.6279
  • Authors: Junzhi Zhu, Mengwu Huo, Yubin Wang, Yuxin Zhai, Lili Hu, Haiyun Huang, Xiu Zhang, Baixu Xiang, Mengdi Zhang, Yusong Gan, Zhiyuan An, Meng Wang, Qihua Xiong, Haiyun Liu
  • Affiliations: Tsinghua University, Collaborative Innovation Center of Quantum Matter, Beijing Academy of Quantum Information Sciences, Sun Yat-Sen University, Chinese Academy of Sciences, Frontier Science Center for Quantum Information, University of Chinese Academy of Sciences
  • Link: http://arxiv.org/abs/2604.02843v1
  • Paper page: High-energy electronic excitations in La₃Ni₂O₇ by time-resolved optical spectroscopy

Summary: This study employs time-resolved optical spectroscopy to investigate the ultrafast dynamics of high-energy electronic excitations in bilayer nickelate La₃Ni₂O₇ from 10 K to room temperature at ambient pressure. Two high-energy electronic excitations originating from distinct interband transitions are identified at approximately 1.8 eV and 2.4 eV, revealing different density wave (DW) gaps of about 54 meV and 67 meV, respectively. The relaxation dynamics of these two excited states are well described by the Rothwarf-Taylor model. Additionally, four coherent Raman-active phonon modes are observed, exhibiting varying coupling strengths to the different electronic excitations. The phonon softening upon heating from about 100 K to room temperature can be explained by a semi-quantitative model incorporating thermal expansion and anharmonic phonon-phonon coupling, while the deviation of measured phonon frequencies from the model fit at low temperatures suggests an additional contribution from electron-phonon coupling. This work directly demonstrates the complex gap structure and phonon dynamics in this material, providing key insights into its density wave mechanism and many-body effects.