Dimensionality-induced insulator-metal crossover in layered nickelates Lan+1NinO2n+2 (n = 2, 3, and ∞)
Ting Liu,
Hua Wu,
Ting Jia,
Xiaoli Zhang,
Zhi Zeng,
H. Q. Lin,
X. G. Li
Affiliations
Ting Liu
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Hua Wu
Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of physics, Fudan University, Shanghai 200433, China
Ting Jia
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Xiaoli Zhang
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Zhi Zeng
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
H. Q. Lin
Beijing Computational Science Research Center, Beijing 100084, China
X. G. Li
Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, China
Low-valence layered nickelates are a structural analog to the superconducting cuprates and possess interesting properties. In this work, we have systematically studied the electronic structure of Lan+1NinO2n+2 using first-principles calculations. Our results reveal that the Ni-3d 3z2 − r2 orbital state is active and evolves from discrete molecular levels to a continuous solid band and its filling varies as the dimensionality (or n) increases. The two-dimensional (2D) La3Ni2O6 and La4Ni3O8 are thus found to have a molecular insulating state. In contrast, the 3D LaNiO2 is metallic and its 3z2 − r2 band surprisingly becomes 3D due to the Ni-La hybridization, and the La-5d xy orbital also forms a 2D metallic band. Therefore, Lan+1NinO2n+2 is a dimensionality-controlled insulator-metal crossover system.
