Zhang Xiaoyu, Duzgun Ayhan, Lao Yuyang, Subzwari Shayaan, Bingham Nicholas S, Sklenar Joseph, Saglam Hilal, Ramberger Justin, Batley Joseph T, Watts Justin D, Bromley Daniel, Chopdekar Rajesh V, O'Brien Liam, Leighton Chris, Nisoli Cristiano, Schiffer Peter
Department of Applied Physics, Yale University, New Haven, CT, 06511, USA.
Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Nat Commun. 2021 Nov 11;12(1):6514. doi: 10.1038/s41467-021-26734-6.
One-dimensional strings of local excitations are a fascinating feature of the physical behavior of strongly correlated topological quantum matter. Here we study strings of local excitations in a classical system of interacting nanomagnets, the Santa Fe Ice geometry of artificial spin ice. We measured the moment configuration of the nanomagnets, both after annealing near the ferromagnetic Curie point and in a thermally dynamic state. While the Santa Fe Ice lattice structure is complex, we demonstrate that its disordered magnetic state is naturally described within a framework of emergent strings. We show experimentally that the string length follows a simple Boltzmann distribution with an energy scale that is associated with the system's magnetic interactions and is consistent with theoretical predictions. The results demonstrate that string descriptions and associated topological characteristics are not unique to quantum models but can also provide a simplifying description of complex classical systems with non-trivial frustration.
局部激发的一维弦是强关联拓扑量子物质物理行为的一个迷人特征。在这里，我们研究相互作用的纳米磁体经典系统（人工自旋冰的圣达菲冰几何结构）中的局部激发弦。我们测量了纳米磁体在铁磁居里点附近退火后以及热动态状态下的磁矩构型。虽然圣达菲冰晶格结构复杂，但我们证明其无序磁态在涌现弦的框架内可以自然地描述。我们通过实验表明，弦长遵循简单的玻尔兹曼分布，其能量尺度与系统的磁相互作用相关，并且与理论预测一致。结果表明，弦描述和相关的拓扑特征并非量子模型所独有，还可以为具有非平凡挫折的复杂经典系统提供简化描述。
