AI 中文总结
研究探索巡游电子体系中电子环向金属（ETM）的朗道理论，通过投影不稳定性判据等方法确立其为独特金属朗道相，揭示其磁电响应与赝自旋拓扑的关联及非线性输运特性。
AI 中文摘要
环向序是一种高阶多极序，其在巡游电子体系中的本征实现方式仍未被探索。本文发展了电子环向金属（ETM）的通用理论，其中环向序由费米面附近的电子自由度自发产生。由于候选环向双线性项可通过对称性与均匀电荷电流重叠，我们构建了投影不稳定性判据以排除不可凝聚的电流分量。在该电流正交扇区内，我们在宇称（$\boldsymbol{\textit{P}}$）奇且时间反演（$\boldsymbol{\textit{T}}$）奇的粒子-空穴通道中识别出软集体模式，并证明ETM作为费米液体不稳定性出现。随后，我们通过反对称磁电响应张量定义巡游体系中的环向矩，进一步建立该响应与赝自旋纹理拓扑的密切联系：赝自旋涡旋的重排会改变费米面的缠绕结构，并显著增强磁电响应。ETM还表现出特征性的非线性电荷输运，包括其带间量子几何贡献的显著增强。我们的结果确立ETM为一种独特的金属朗道相，并为理解巡游电子产生的环向序提供通用框架。
英文摘要
Toroidal order is a higher-rank multipolar order whose intrinsic realization in itinerant-electron systems remains unexplored. Here, we develop a generic theory of the electronic toroidal metal (ETM), in which toroidal order emerges spontaneously from electronic degrees of freedom near the Fermi surfaces. Because candidate toroidal bilinears can overlap by symmetry with the uniform charge current, we formulate a projected instability criterion that removes the noncondensable current component. Within this current-orthogonal sector, we identify a soft collective mode in the $\mathcal{P}$-odd and $\mathcal{T}$-odd particle-hole channel and demonstrate that ETM arises as a Fermi-liquid instability. We then define the toroidal moment in an itinerant system through the antisymmetric magnetoelectric response tensor. We further establish an intimate connection between this response and the topology of pseudospin texture: the rearrangement of pseudospin vortices changes the winding structure of the Fermi surfaces and markedly enhances the magnetoelectric response. ETM also exhibits characteristic nonlinear charge transport, including a pronounced enhancement of its interband quantum-geometric contribution. Our results establish ETM as a distinct metallic Landau phase and provide a general framework for understanding toroidal order generated by itinerant electrons.
Comments14 pages, 6 figures
