论文标题
磁性超材料中的紧急三个临界性
Emergent tri-criticality in magnetic metamaterials
论文作者
论文摘要
在100 nm量表上设计的金属盘具有内部磁纹理，从完全磁化的状态到零矩零矩的涡流状态变化。这种内部结构与二盘相互作用之间的相互作用是在由磁盘的平方阵列制成的磁化材料中研究的。质地是由o（2）对称性变化的中旋模建模的，而在中旋蛋白之间，最近的邻居耦合。研究了模型的热力学特性，并发现了从Kosterlitz-通过明显的三临界点从kosterlitz到第一阶的订购过渡。表征有限尺寸磁化的有效临界指数从2D-XY模型的值演变为在三个临界点的该值的一半。讨论了对未来实验的后果。
Metallic discs engineered on the 100 nm scale have an internal magnetic texture which varies from a fully magnetized state to a vortex state with zero moment. The interplay between this internal structure and the inter-disc interactions is studied in magnetic metamaterials made of square arrays of the magnetic discs. The texture is modeled by a mesospin of varying length with O(2) symmetry and the inter-disc interaction by a nearest neighbour coupling between mesospins. The thermodynamic properties of the model are studied numerically and an ordering transition is found which varies from Kosterlitz-Thouless to first order via an apparent tri-critical point. The effective critical exponent characterising the finite size magnetization evolves from the value for the 2D-XY model to less than half this value at the tri-critical point. The consequences for future experiments both in and out of equilibrium are discussed.
