发表机构
Max Planck Institute for the Physics of Complex Systems（马克斯·普朗克复杂系统物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在双轨道Hubbard-Kanamoni模型中揭示了激子条纹序这一新的对称破缺态，发现Hund耦合符号决定自旋特征，掺杂产生非公度纹理，晶体场劈裂可稳定三重态激子序。
AI 中文摘要
激子凝聚和条纹形成是电子关联的两种不同表现。虽然激子序自然出现在多轨道系统中，条纹序则是掺杂关联电子模型的显著特征。在此，我们研究了正方晶格上双轨道Hubbard-Kanamoni模型中激子条纹序的类似物，其特征为轨道间粒子-空穴相干性的空间调制，以及在轨道宇称对称极限下，相对轨道$\mathbb{Z}_2$对称性的自发破缺。利用无限制实空间Hartree-Fock计算并结合随机相位近似不稳定性分析，我们确定了Kanamoni相互作用如何选择不同的激子通道。Hund交换的符号控制凝聚体的自旋特征：铁磁Hund耦合有利于三重态激子序，而反铁磁Hund耦合则稳定单重态激子序。在掺杂时，公度激子密度波发展出非公度纹理，包括激子条纹，以及在三重态通道中的螺旋激子密度波。我们进一步表明，晶体场劈裂通过修改轨道间嵌套强烈地重组激子不稳定性，并且即使在缺乏对跳跃的情况下也能稳定三重态激子序。我们的结果确立了激子条纹作为多轨道关联系统的一种独特对称破缺态，并识别了其稳定的微观途径。
英文摘要
Excitonic condensation and stripe formation are two distinct manifestations of electronic correlations. While excitonic order naturally arises in multi-orbital systems, stripe order is a prominent feature of doped correlated-electron models. Here, we investigate an excitonic analogue of stripe order in the two--orbital Hubbard-Kanamori model on the square lattice, characterized by a spatial modulation of inter-orbital particle-hole coherence and, in the orbital-parity-symmetric limit, spontaneous breaking of a relative orbital $\mathbb{Z}_2$ symmetry. Using unrestricted real-space Hartree-Fock calculations complemented by random-phase-approximation instability analysis, we determine how the Kanamori interactions select different excitonic channels. The sign of Hund's exchange controls the spin character of the condensate: ferromagnetic Hund coupling favors triplet excitonic order, whereas antiferromagnetic Hund coupling stabilizes singlet excitonic order. Upon doping, commensurate excitonic density waves develop incommensurate textures, including excitonic stripes and, in the triplet sector, spiral excitonic density waves. We further show that crystal-field splitting strongly reorganizes the excitonic instability by modifying inter-orbital nesting and can stabilize triplet excitonic order even in the absence of pair hopping. Our results establish excitonic stripes as a distinct symmetry-broken state of multi-orbital correlated systems and identify microscopic routes for their stabilization.
Comments24 pages; 13 Figures. Comments are welcome
