Evolution of Electronic Correlations in the Ruddlesden-Popper Nickelates

Zhe Liu; Jie Li; Mengwu Huo; Bingke Ji; Jiahao Hao; Yaomin Dai; Mengjun Ou; Qing Li; Hualei Sun; Bing Xu; Yi Lu; Meng Wang; Hai-Hu Wen

paper

Evolution of Electronic Correlations in the Ruddlesden-Popper Nickelates

arXiv:2411.08539

Abstract

We report on optical studies of the Ruddlesden-Popper nickelates La $_{n + 1}$ Ni $_{n}$ O $_{3 n + 1}$ with $n = 2$ (La $_{3}$ Ni $_{2}$ O $_{7}$ ), $n = 3$ (La $_{4}$ Ni $_{3}$ O $_{10}$ ) and $n = \infty$ (LaNiO $_{3}$ ). As the number of the NiO $_{6}$ octahedra layers $n$ grows, the ratio of the kinetic energy determined from the experimental optical conductivity and that from band theory $K_{exp} / K_{band}$ increases, suggesting a reduction of electronic correlations. While the strong electronic correlations in the bilayer La $_{3}$ Ni $_{2}$ O $_{7}$ place it on the verge of the Mott insulating phase, the trilayer La $_{4}$ Ni $_{3}$ O $_{10}$ and infinite-layer LaNiO $_{3}$ exhibit moderate electronic correlations, falling into the regime of correlated metals. The evolution of the electronic correlations in La $_{n + 1}$ Ni $_{n}$ O $_{3 n + 1}$ is likely to be dominated by the Ni- $d_{z^{2}}$ orbital. Our results provide important information for understanding the superconductivity in Ruddlesden-Popper nickelates.

7 pages, 4 figures. Comments are welcome and appreciated