Electronic correlations and partial gap in the bilayer nickelate La3Ni2O7

• Published in: Nature communications 2024-08, Vol.15 (1), p.7570-8, Article 7570
• Main Authors: Liu, Zhe, Huo, Mengwu, Li, Jie, Li, Qing, Liu, Yuecong, Dai, Yaomin, Zhou, Xiaoxiang, Hao, Jiahao, Lu, Yi, Wang, Meng, Wen, Hai-Hu
• Format: Article
• Language: English
• Subjects: 639/301/119/1003; 639/301/119/995; Band theory; Correlation; Crystals; Fermi liquids; Fermi surfaces; Humanities and Social Sciences; Kinetic energy; multidisciplinary; Pressure; Science; Science (multidisciplinary); Single crystals; Superconductivity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-52001-5

The discovery of superconductivity with a critical temperature of about 80 K in La 3 Ni 2 O 7 single crystals under pressure has received enormous attention. La 3 Ni 2 O 7 is not superconducting under ambient pressure but exhibits a transition at T   ∗  ≃ 115 K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities. Here, our optical study shows that La 3 Ni 2 O 7 features strong electronic correlations which significantly reduce the electron’s kinetic energy and place this system in the proximity of the Mott phase. The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level. The transition at T   ∗ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected. These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni- d 3 z 2 − r 2 orbital is removed due to the transition at T   ∗ . Our experimental results provide pivotal information for understanding the transition at T   ∗ and superconductivity in La 3 Ni 2 O 7 . The bilayer nickelate La 3 Ni 2 O 7 was recently shown to be superconducting at high-pressure. Here the authors reveal strong electronic correlations and the opening of a partial gap, providing key information for understanding the nature of the density-wavelike transition at ambient pressure and superconductivity in this compound.