Dantas Vitor, Andrade Eric C
Instituto de Física de São Carlos, Universidade de São Paulo, C.P. 369, São Carlos, SP 13560-970, Brazil.
Phys Rev Lett. 2022 Jul 15;129(3):037204. doi: 10.1103/PhysRevLett.129.037204.
The Kitaev model is a fascinating example of an exactly solvable model displaying a spin-liquid ground state in two dimensions. However, deviations from the original Kitaev model are expected to appear in real materials. In this Letter, we investigate the fate of Kitaev's spin liquid in the presence of disorder-bond defects or vacancies-for an extended version of the model. Considering static flux backgrounds, we observe a power-law divergence in the low-energy limit of the density of states with a nonuniversal exponent. We link this power-law distribution of energy scales to weakly coupled droplets inside the bulk, in an uncanny similarity to the Griffiths phase often present in the vicinity of disordered quantum phase transitions. If time-reversal symmetry is broken, we find that power-law singularities are tied to the destruction of the topological phase of the Kitaev model in the presence of bond disorder alone. However, there is a transition from this topologically trivial phase with power-law singularities to a topologically nontrivial one for weak to moderate site dilution. Therefore, diluted Kitaev materials are potential candidates to host Kitaev's chiral spin-liquid phase.
基塔耶夫模型是二维中展现自旋液体基态的精确可解模型的一个引人入胜的例子。然而，预计实际材料中会出现与原始基塔耶夫模型的偏差。在本信函中，我们针对该模型的一个扩展版本，研究了在存在无序键缺陷或空位的情况下基塔耶夫自旋液体的命运。考虑静态磁通背景，我们在态密度的低能极限中观察到具有非普适指数的幂律发散。我们将这种能量尺度的幂律分布与体内部的弱耦合液滴联系起来，这与无序量子相变附近经常出现的格里菲斯相有着惊人的相似性。如果时间反演对称性被打破，我们发现幂律奇点与仅存在键无序时基塔耶夫模型拓扑相的破坏相关。然而，对于弱到中等程度的格点稀释，存在从这个具有幂律奇点的拓扑平凡相到拓扑非平凡相的转变。因此，稀释的基塔耶夫材料是容纳基塔耶夫手性自旋液体相的潜在候选者。
