论文标题
具有自发损坏的SU(2) - 对称性的多电子系统的动力学顶点近似
The dynamical vertex approximation for many-electron systems with spontaneously broken SU(2)-symmetry
论文作者
论文摘要
我们概括了动力学顶点近似(D $γ$ a)的形式 - 动态平均场理论(DMFT)的图表扩展 - 以治疗磁有序的相。为此,我们首先简明地说明了许多电子形式主义,用于在SU(2) - 对称的系统中对Feynman图进行梯子重新调整,该系统与铁磁(FM)或抗Firomagnetic(FM)或抗Firomagnetic(AF)顺序相关。然后,我们分析了通过在伯特 - 钙板方程中使用两粒子不可约的顶点函数的局部近似引入的算法简化,从而定义了用于磁系统的d $γ$ A的梯子实现。明确讨论了该假设与大量协调数/高维度的DMFT极限的关系。作为最后一步,我们在Hubbard模型的FM和AF级阶段中得出了梯子D $γ$的表达式。基于d $γ$ a方程的静态均值输入,通过近似计算明确说明了在AF排序情况下出现的物理学。结果获得了二维抗铁磁体的金属和绝缘基态的捕获基本方面,为我们的方法提供了可靠的指南针,可为未来,更广泛的应用。在结论中简要概述了相关电子系统中磁相的基于图的磁相处理的可能路线。
We generalize the formalism of the dynamical vertex approximation (D$Γ$A) -- a diagrammatic extension of the dynamical mean-field theory (DMFT)-- to treat magnetically ordered phases. To this aim, we start by concisely illustrating the many-electron formalism for performing ladder resummations of Feynman diagrams in systems with broken SU(2)-symmetry, associated to ferromagnetic (FM) or antiferromagnetic (AF) order. We then analyze the algorithmic simplifications introduced by taking the local approximation of the two-particle irreducible vertex functions in the Bethe-Salpeter equations, which defines the ladder implementation of D$Γ$A for magnetic systems. The relation of this assumption with the DMFT limit of large coordination-number/ high-dimensions is explicitly discussed. As a last step, we derive the expression for the ladder D$Γ$A self-energy in the FM- and AF-ordered phases of the Hubbard model. The physics emerging in the AF-ordered case is explicitly illustrated by means of approximated calculations based on a static mean-field input for the D$Γ$A equations. The results obtained capture fundamental aspects of both metallic and insulating ground states of two-dimensional antiferromagnets, providing a reliable compass for future, more extensive applications of our approach. Possible routes to further develop diagrammatic-based treatments of magnetic phases in correlated electron systems are briefly outlined in the conclusions.