Looking for a crystalline 2D spin ice Spin ices—materials in which local magnetic spins respect “ice rules” similar to those in water ice—are typically three-dimensional. Two-dimensional (2D) ice rules can also be formulated and have been found to be satisfied in engineered nanomagnetic systems, usually referred to as artificial spin ices. Zhao et al. used neutron scattering and thermodynamic measurements to study a crystalline candidate for a 2D spin ice, the intermetallic compound HoAgGe. They found that at low temperatures, the local spins on the distorted kagome planes of this quasi-2D material respect 2D ice rules. Increasing the temperature led to a series of transitions consistent with theoretical expectations. Science, this issue p. 1218 Neutron scattering and thermodynamic measurements suggest that HoAgGe is a crystalline two-dimensional spin ice. Spin ices are exotic phases of matter characterized by frustrated spins obeying local “ice rules,” in analogy with the electric dipoles in water ice. In two dimensions, one can similarly define ice rules for in-plane Ising-like spins arranged on a kagome lattice. These ice rules require each triangle plaquette to have a single monopole and can lead to different types of orders and excitations. Using experimental and theoretical approaches including magnetometry, thermodynamic measurements, neutron scattering, and Monte Carlo simulations, we establish HoAgGe as a crystalline (i.e., nonartificial) system that realizes the kagome spin ice state. The system features a variety of partially and fully ordered states and a sequence of field-induced phases at low temperatures, all consistent with the kagome ice rule.

中文翻译：

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在受挫金属间化合物中实现 Kagome 自旋冰态

寻找晶体 2D 自旋冰 自旋冰——其中局部磁自旋遵循类似于水冰的“冰规则”的材料——通常是三维的。二维 (2D) 冰规则也可以制定，并且已经发现在工程纳米磁性系统中得到满足，通常称为人工自旋冰。赵等人。使用中子散射和热力学测量来研究 2D 自旋冰的晶体候选物，即金属间化合物 HoAgGe。他们发现，在低温下，这种准二维材料扭曲的 kagome 平面上的局部自旋遵循二维冰规则。升高温度导致一系列与理论预期一致的转变。科学，这个问题 p。1218 中子散射和热力学测量表明 HoAgGe 是一种晶体二维自旋冰。自旋冰是物质的奇异相，其特征是受挫的自旋遵循局部“冰规则”，类似于水冰中的电偶极子。在二维中，我们可以类似地为排列在 kagome 晶格上的平面内类伊辛自旋定义冰规则。这些冰规则要求每个三角形板都有一个单极子，并且可以导致不同类型的阶次和激发。使用包括磁力测量、热力学测量、中子散射和蒙特卡罗模拟在内的实验和理论方法，我们将 HoAgGe 建立为实现 Kagome 自旋冰状态的结晶（即非人工）系统。