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arXiv · 2408.12042

Correlation Effects in a Simplified Bilayer Two-Orbital Hubbard Model at Half Filling

Jian-Jian Yang·Dao-Xin Yao·Han-Qing Wu
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Abstract

Motivated by the discovery of high-temperature superconductivity in bilayer nickelate La$_3$Ni$_2$O$_7$ under pressure, we investigate the ground-state phase diagram and correlation effects using determinant quantum Monte Carlo simulations in a simplified bilayer two-orbital Hubbard model at half filling. Our results reveal the emergence of a nonmagnetic weakly insulating phase at weak on-site Hubbard interactions, transitioning to an antiferromagnetic Mott insulating phase as the interaction strength exceeds a critical value $U/t_1^x\approx 4.15$. This phase transition is consistent with the 3D O(3) Heisenberg universality class. Additionally, we analyze dynamical properties such as the single-particle spectral function and dynamic spin structure factor. The pronounced inter-layer correlation of $d_{3z^2-r^2}$ orbitals results in a downward trend and an extended flatness in the $\gamma$ band, mirroring the angle-resolved photoemission spectroscopy findings under ambient pressure. Our numerical results provide important clues for understanding the strong correlation effects in La$_3$Ni$_2$O$_7$.

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Jian-Jian Yang, Dao-Xin Yao, Han-Qing Wu. 2024-08-22. Correlation Effects in a Simplified Bilayer Two-Orbital Hubbard Model at Half Filling. https://doi.org/10.1103/physrevb.110.235155

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