AI 中文总结
研究混合镍酸盐La₅Ni₃O₁₁超导性，通过基于对称性的唯象方法分析其低能物理，发现超导具双能隙性质，T_c降低因层间配对贡献减小，据此探讨了可能的配对机制及γ口袋作用。
AI 中文摘要
近期实验报道了混合镍酸盐La₅Ni₃O₁₁中的高温超导性，它由双层La₃Ni₂O₇和单层La₂NiO₄交替堆叠组成。然而，La₅Ni₃O₁₁的超导转变温度T_c约64K，显著低于加压的La₃Ni₂O₇的80K。为此，本文开发了一种基于对称性的唯象方法，通过电荷自洽密度泛函理论加动态平均场理论方法系统分析La₅Ni₃O₁₁的低能物理。结果表明其超导性具有双能隙性质，由d_z²轨道间的主导层间配对和d_x² - y²轨道间的次主导层内配对组成。T_c降低归因于层间配对贡献减小。基于此统一图景，讨论了镍酸盐超导体双层NiO₂平面超导可能的配对机制及γ口袋的作用。
英文摘要
Recent experiments report high-temperature superconductivity in the hybrid nickelate $\mathrm{La}_5\mathrm{Ni}_3\mathrm{O}_{11}$, which is composed of alternating stacks of bilayer $\mathrm{La}_3\mathrm{Ni}_2\mathrm{O}_7$ and monolayer $\mathrm{La}_2\mathrm{NiO}_4$. However, the superconducting transition temperature $T_c \approx 64~\mathrm{K}$ for $\mathrm{La}_5\mathrm{Ni}_3\mathrm{O}_{11}$ is remarkably lower than the $80~\mathrm{K}$ observed for pressurized $\mathrm{La}_3\mathrm{Ni}_2\mathrm{O}_7$. Thus, an unified microscopic theory is required to address the difference in the pairing mechanisms between these systems. Here, we develop a phenomenological symmetry-based approach to systematically analyze the low-energy physics in $\mathrm{La}_5\mathrm{Ni}_3\mathrm{O}_{11}$, which is obtained by a charge self-consistent density functional theory plus dynamical mean-field theory method. We show that the superconductivity in $\mathrm{La}_5\mathrm{Ni}_3\mathrm{O}_{11}$ exhibits a two-gap nature, consisting of a leading interlayer pairing between the $d_{z^2}$ orbitals and a subleading intralayer pairing between the $d_{x^2-y^2}$ orbitals. The reduction of $T_c$ can be attributed to the diminished contribution of the interlayer pairing, as reflected by the hopping parameter ratio $|t_{\perp}^z/t_{\parallel}^{x}|$. Base on this unified picture, we discuss the possible pairing mechanism and the role of $γ$ pocket for the superconductivity in the bilayer NiO$_2$ planes of nickelate superconductors.
Comments5 pages, 4 figures
