镍基327超导体的弱耦合理论
Weak coupling theory of nickel-based 327 superconductors
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中文总结 AI 辅助
该综述聚焦加压镍酸盐双层体系$La_{3}Ni_{2}O_{7}$的超导性，研究随机相位近似、涨落交换近似、函数重整化群三种弱耦合理论框架，分析其低能电子结构的配对相互作用与不稳定性，为非常规超导研究提供新范例。
中文摘要 AI 辅助
本综述全面考察了用于理解加压镍酸盐双层体系$La_{3}Ni_{2}O_{7}$中涌现的超导性的弱耦合理论方法。在高压下该材料的高Tc超导性被里程碑式发现后，它迅速成为非常规超导领域的新范例平台，加入铜基和铁基体系。我们聚焦三个关键理论框架：随机相位近似（RPA）、涨落交换近似（FLEX）和函数重整化群（FRG），这些方法用于分析由包含Ni $d_{x^2-y^2}$和$d_{3z^2-r^2}$轨道的双层两轨道哈伯德哈密顿量描述的低能电子结构产生的有效配对相互作用与涌现不稳定性。
英文摘要
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.
