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arXiv · 2504.10114

$t$-$J$ model for strongly correlated two-orbital systems: Application to bilayer nickelate superconductors

Tatsuya Kaneko·Masataka Kakoi·Kazuhiko Kuroki
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Abstract

We derive a $t$-$J$ model applicable to strongly correlated two-orbital systems including bilayer nickelate superconductors. Using the Schrieffer-Wolff transformation, we exclude the doubly occupied states, which raise the onsite Coulomb energy, and derive the resulting spin interactions from the two-orbital Hubbard model. We also introduce effective interactions attributed to the interorbital Coulomb interaction. To adapt the effective model to bilayer nickelates that exhibit high-temperature superconductivity, we quantitatively evaluate the strengths of the spin interactions based on the hopping parameters in La$_3$Ni$_2$O$_7$. Considering the evaluated effective interactions, we propose a simplified $t$-$J$ model for bilayer nickelate superconductors.

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Tatsuya Kaneko, Masataka Kakoi, Kazuhiko Kuroki. 2025-04-14. $t$-$J$ model for strongly correlated two-orbital systems: Application to bilayer nickelate superconductors. https://doi.org/10.1103/bsgt-sg2s

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