Author:
Shen 沈 Yang 阳,Qin 秦 Mingpu 明普,Zhang 张 Guang-Ming 广铭
Abstract
High-T
c superconductivity with possible T
c ≈ 80 K has been reported in the single crystal of La3Ni2O7 under high pressure. Based on the electronic structure given by the density functional theory calculations, we propose an effective bi-layer model Hamiltonian including both 3d
z
2
and 3d
x
2–y
2
orbital electrons of the nickel cations. The main feature of the model is that the 3d
z
2
electrons form inter-layer σ-bonding and anti-bonding bands via the apical oxygen anions between the two layers, while the 3d
x
2–y
2
electrons hybridize with the 3d
z
2
electrons within each NiO2 plane. The chemical potential difference of these two orbital electrons ensures that the 3d
z
2
orbitals are close to half-filling and the 3d
x
2–y
2
orbitals are near quarter-filling. The strong on-site Hubbard repulsion of the 3d
z
2
orbital electrons gives rise to an effective inter-layer antiferromagnetic spin super-exchange J. Applying pressure can self dope holes on the 3d
z
2
orbitals with the same amount of electrons doped on the 3d
x
2–y
2
orbitals. By performing numerical density-matrix renormalization group calculations on a minimum setup and focusing on the limit of large J and small doping of 3d
z
2
orbitals, we find the superconducting instability on both the 3d
z
2
and 3d
x
2–y
2
orbitals by calculating the equal-time spin singlet pair–pair correlation function. Our numerical results may provide useful insights in the high-T
c superconductivity in single crystal La3Ni2O7 under high pressure.
Subject
General Physics and Astronomy
Cited by
6 articles.
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