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arXiv 2202.06158cond-mat.str-el
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任意磁场方向Kitaev模型的Phase Diagrams

Phase Diagrams of Kitaev Models for Arbitrary Magnetic-Field Orientations

F. Yılmaz, A. P. Kampf, S. K. Yip

摘要:

Kitaev模型是一个严格可解的量子自旋模型,其语言是受约束的实费米子。尽管沿着特殊的磁场方向进行了大量的研究,但关于完整的场角表征的知识有限,这可以提供关于存在分数激励的有价值的信息。为此,我们首先扩展了以前的铁磁Kitaev模型的反铁磁版本的场角响应的研究。然而,候选Kitaev材料的现实描述,在边共享八面体范例,需要额外的耦合项,包括一个大的非对角项$Γ$以及可能的各向异性校正$Γ_p$。因此,这是不够的,依赖于裸露的Kitaev模型的拓扑特性作为唯一的源所观察到的热霍尔电导率信号和理解这些扩展Kitaev模型与一个完整的字段响应是必需的。从实际的K-$Γ$- $Γ_p$模型的零场相图出发,我们识别出反铁磁之字形和(部分)极化相以及两个不寻常的Kitaev(- $Γ$)自旋液相。这些相位对于任意场取向的磁场响应提供了非常丰富的相图。在两个有序相之间存在一个部分极化相,这两个有序相具有抑制的磁化强度、有限的分形和有限的陈氏数。该相的特征在于扩展的Kitaev- $Γ$自旋液体。为了符合我们的研究结果与实验,我们重现的不对称性的程度的中间阶段,特别是对于两个不同的字段方向$θ= \pm 60^o$。

英文摘要:

The Kitaev model is an exactly solvable quantum spin model within the language of the constrained real fermions. In spite of numerous studies along special magnetic-field orientations, there is a limited amount of knowledge on the complete field-angle characterization, which can provide valuable information on the existence of fractionalized excitations. For this purpose, we first extend previous studies on the field-angle response of the ferromagnetic Kitaev model to its antiferromagnetic version. Yet, the realistic description of the candidate Kitaev materials, within the edge-sharing octahedra paradigm, require additional coupling terms, including a large off-diagonal term $Γ$ along with possible anisotropic corrections $Γ_p$. It is therefore not sufficient to depend on the topological properties of the bare Kitaev model as the only source for the observed thermal Hall conductivity signals and an understanding of these extended Kitaev models with a complete field response is demanded. Starting from the zero-field phase diagram of realistic K-$Γ$-$Γ_p$ models, we identify antiferromagnetic zig-zag and (partially) polarized phases as well as two unusual Kitaev(-$Γ$) spin-liquid phases. The magnetic field response of these phases for arbitrary field orientations provides a remarkably rich phase diagram. A partially polarized phase is revealed between two ordered phases with a suppressed magnetization, finite fractionalization and finite Chern number. This phase is characterized as an extended Kitaev-$Γ$ spin-liquid. To comply our findings with experiments, we reproduce the asymmetry in the extent of the intermediate phases specifically for the two different field directions $θ= \pm 60^o$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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