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arXiv · 2608.22759

Weak coupling theory of nickel-based 327 superconductors

Miao Jianjian·Chen Weiqiang
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Abstract

This review provides a comprehensive survey of weak-coupling theoretical approaches applied to understand the emergent superconductivity in the pressurized nickelate bilayer system $La_{3}Ni_{2}O_{7}$. Following the landmark discovery of its high-Tc superconductivity under pressure, this material has rapidly become a new paradigmatic platform in the field of unconventional superconductivity, joining cuprates and iron-based systems. We focus on three pivotal theoretical frameworks: the random phase approximation (RPA), the fluctuation-exchange approximation (FLEX), and the functional renormalization group (FRG). These methods are deployed to analyze the effective pairing interactions and emergent instabilities arising from the low-energy electronic structure, which is commonly modeled by a bilayer two-orbital Hubbard Hamiltonian incorporating the Ni $d_{x^2-y^2}$ and $d_{3z^2-r^2}$ orbitals.

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Miao Jianjian, Chen Weiqiang. 2026-08-24. Weak coupling theory of nickel-based 327 superconductors. https://doi.org/10.7498/aps.75.20251361

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