Superexchange and charge transfer in the nickelate superconductor La3Ni2O7 under pressure

• Published in: Science China. Physics, mechanics & astronomy mechanics & astronomy, 2024-11, Vol.67 (11), p.117402, Article 117402
• Main Authors: Wú, Wéi, Luo, Zhihui, Yao, Dao-Xin, Wang, Meng
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Astronomy; Charge transfer; Classical and Continuum Physics; Couplings; Cuprates; Doping; Electrons; Energy; Mean field theory; Observations and Techniques; Orbitals; Physics; Physics and Astronomy; Superconductivity; Transition temperature; Transition temperatures
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-023-2300-4

Recently, a bulk nickelate superconductor La 3 Ni 2 O 7 is discovered at pressures with a remarkable high transition temperature T c ∼ 80 K. Here, we study a Hubbard model with tight-binding parameters derived from ab initio calculations of La 3 Ni 2 O 7 , by employing large scale determinant quantum Monte Carlo and cellular dynamical mean-field theory. Our result suggests that the superexchange couplings in this system are comparable to that of cuprates. The system is a charge transfer insulator as the hole concentration becomes four per site at large Hubbard U . Upon hole doping, two low-energy spin-singlet bands emerge in the system exhibiting distinct correlation properties: while the one composed of the out-of-plane Ni- d 3 z 2 − r 2 and O- p z orbitals demonstrates strong antiferromagnetic correlations and narrow effective bandwidth, the in-plane singlet band consisting of the Ni- d x 2 − y 2 and O- p x / p y orbitals is in general more itinerant. Over a broad range of hole doping, the doped holes occupy primarily the d x 2 − y 2 and p x / p y orbitals, whereas the d 3 z 2 − r 2 and p z orbitals retain underdoped. We propose an effective t - J model to capture the relevant physics and discuss the implications of our result for comprehending the La 3 Ni 2 O 7 superconductivity.