论文标题

经典沮丧的Kagome旋转模型中的分裂激发

Fracton excitations in classical frustrated kagome spin models

论文作者

Hering, Max, Yan, Han, Reuther, Johannes

论文摘要

分区是拓扑的准颗粒,其迁移率有限。尽管存在各种托管这些激发的模型,但典型的分布系统需要相当复杂的多粒子相互作用。在这里,我们在经典的Kagome旋转模型的更常见的物理环境中讨论了分子行为,仅具有沮丧的两体相互作用。我们研究了具有不同类型的基本自旋程度的自由度(三态POTTS,XY和海森堡旋转)的系统,这些系统都表现出特征性的子系统对称性和类似法拉克顿的激发。与已知的I型或II型Fracton模型相比,在三州POTTS模型中,分离的分布量和结合的分裂对的迁移率约束截然不同。人们仍然可以用I型法族人行为来解释这些属性,并在将系统视为3D立方晶格模型的2D切割时,构建有效的低能张量表理论。我们广泛的经典蒙特卡洛模拟进一步表明了一个跨温度玻璃相的交叉,该系统被捕获在亚稳态的法氏剂状态中。继续进行XY旋转,我们发现除了分布量外,系统还托管了分数涡流激发。由于两种缺陷的迁移率受到限制,我们的经典蒙特卡洛模拟并未表明kosterlitz-无尽的过渡,但再次显示出玻璃状低温状态的交叉。最后,在海森伯格旋转的情况下,与面部相关的能源屏障消失了,因此缺陷状态可能会不断腐烂到基态。然而,这些衰变表现出幂律放松行为,从而导致低温下的平衡动力学缓慢。

Fractons are topological quasiparticles with limited mobility. While there exists a variety of models hosting these excitations, typical fracton systems require rather complicated many-particle interactions. Here, we discuss fracton behavior in the more common physical setting of classical kagome spin models with frustrated two-body interactions only. We investigate systems with different types of elementary spin degrees of freedom (three-state Potts, XY, and Heisenberg spins) which all exhibit characteristic subsystem symmetries and fracton-like excitations. The mobility constraints of isolated fractons and bound fracton pairs in the three-state Potts model are, however, strikingly different compared to the known type-I or type-II fracton models. One may still explain these properties in terms of type-I fracton behavior and construct an effective low-energy tensor gauge theory when considering the system as a 2D cut of a 3D cubic lattice model. Our extensive classical Monte-Carlo simulations further indicate a crossover into a low temperature glassy phase where the system gets trapped in metastable fracton states. Moving on to XY spins, we find that in addition to fractons the system hosts fractional vortex excitations. As a result of the restricted mobility of both types of defects, our classical Monte-Carlo simulations do not indicate a Kosterlitz-Thouless transition but again show a crossover into a glassy low-temperature regime. Finally, the energy barriers associated with fractons vanish in the case of Heisenberg spins, such that defect states may continuously decay into a ground state. These decays, however, exhibit a power-law relaxation behavior which leads to slow equilibration dynamics at low temperatures.

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