Superexchange and charge transfer in the nickelate superconductor La_(3)Ni_(2)O_(7) under pressure  

作　　者：Wéi Wú Zhihui Luo Dao-Xin Yao Meng Wang 

机构地区：[1]Center for Neutron Science and Technology,Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices,School of Physics,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2024年第11期1-8,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 12274472, 92165204, 12174454, and 11974432);the National Key Research and Development Program of China (Grant Nos. 2022YFA1402802, and 2018YFA0306001);the Guangdong Basic and Applied Basic Research Foundation (Grant Nos. 2022A1515011618, and 2021B1515120015);the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices (Grant No. 2022B1212010008);the Shenzhen International Quantum Academy (Grant No. SIQA202102);the Leading Talent Program of Guangdong Special Projects (Grant No. 201626003);the support from GuangZhou National Supercomputing Center (Tianhe-Ⅱ)。

摘　　要：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_(3z^(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_(3z^(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.

关 键 词：superconductivity nickelate superconductors Hubbard model SUPEREXCHANGE charge transfer insulator quantum Monte Carlo 

分 类 号：O469[理学—凝聚态物理]