AI 中文总结
研究加压La₃Ni₂O₇超导能隙对称性，结合单格点双轨道DMFT与自能重整化RPA，通过替换粒子-空穴泡及相关计算，发现强关联对超导配对对称性起关键作用，正确处理关联重整化准粒子很重要。
AI 中文摘要
加压La₃Ni₂O₇的超导能隙对称性尚未确定，因为传统弱耦合计算常使该系统接近竞争的符号变化s波和d波不稳定性。我们使用夏等人的四轨道万尼尔哈密顿量，将单格点双轨道动态平均场理论（DMFT）与自能重整化随机相位近似（RPA）相结合。核心步骤是用G_DMFTG_DMFT泡替换普通RPA的裸粒子-空穴泡G_0G_0，同时保留相同的残余斯莱特-金莫里相互作用顶点。在裸RPA基准中，主导配对本征值属于B₂g d_xy通道。一旦包含DMFT自能，层级反转：A₁g符号变化的s₊₋态占主导，B₁g d_x²-y²通道次之，原始B₂g不稳定性被强烈抑制。口袋对分解和轨道分辨磁化率表明，这种反转源于d_3z²-r²扇区的轨道选择性重整化，它过滤了在裸RPA中稳定d_xy配对的γ口袋散射过程，同时保留有利于s₊₋配对的分布式口袋间过程。作为独立的双粒子验证，我们使用具有局部DMFT顶点的对偶贝塞-萨尔皮特方程进一步计算静态自旋磁化率。所得磁化率保留了广泛的有限动量磁响应，且在Γ附近较弱，增强了关联稳定的s₊₋态的自旋涨落背景。我们的结果表明，强关联在La₃Ni₂O₇中不是次要修正：对关联重整化准粒子的适当处理对于预测超导配对对称性至关重要。
英文摘要
The superconducting gap symmetry of pressurized La$_3$Ni$_2$O$_7$ remains unsettled because conventional weak-coupling calculations often place the system close to competing sign-changing $s$- and $d$-wave instabilities. Using the four-orbital Wannier Hamiltonian of Xia et al., we combine single-site two-orbital dynamical mean-field theory (DMFT) with a self-energy-renormalized random-phase approximation (RPA). The central step is to replace the bare particle-hole bubble $G_0G_0$ of ordinary RPA by a $G_{\rm DMFT}G_{\rm DMFT}$ bubble, while keeping the same residual Slater--Kanamori interaction vertices. In the bare RPA benchmark, the leading pairing eigenvalue belongs to the $B_{2g}$ $d_{xy}$ channel. Once the DMFT self-energy is included, the hierarchy is reversed: the $A_{1g}$ sign-changing $s_{\pm}$ state becomes dominant, the $B_{1g}$ $d_{x^2-y^2}$ channel is subleading, and the original $B_{2g}$ instability is strongly suppressed. Pocket-pair decomposition and orbital-resolved susceptibilities show that the reversal originates from orbital-selective renormalization of the $d_{3z^2-r^2}$ sector, which filters the $γ$-pocket scattering processes that stabilize $d_{xy}$ pairing in bare RPA while preserving distributed inter-pocket processes favorable to $s_{\pm}$ pairing. As an independent two-particle validation, we further compute the static spin susceptibility using the dual Bethe--Salpeter equation with the local DMFT vertex. The resulting susceptibility retains a broad finite-momentum magnetic response and is weak near $Γ$, strengthening the spin-fluctuation background for the correlation-stabilized $s_{\pm}$ state. Our results demonstrate that strong correlations are not a secondary correction in La$_3$Ni$_2$O$_7$: an appropriate treatment of correlation-renormalized quasiparticles is essential for predicting the superconducting pairing symmetry.
Comments11 pages, 5 figures
