基态四重简并四方人工自旋冰的设计与理论研究

As an emerging hot topic, artificial spin ice has opened a new window to study the collective phenomena and the quasi-particle excitations in condensed matter physics. Moreover, the excited monopoles in artificial spin ice have shown high potential for energy storage, information transmission and logic devices. In this project, we focus on the design and theoretical study of the four-fold degenerate artificial square spin ice. The project will begin with the newly designed artificial square spin ice, in which the local vertex frustration, the ground state configuration and the magnetic of the system will be modulated by modifying the in-plane positions of artificial spins. Furthermore, we will investigate the thermodynamic properties of the redesigned system by using varies numerical simulation algorithms and reveal the new principles that dominate the dynamic process of the excited monopoles. Finally, the new designed model will provide approaches to exploring the topological domain vertex in artificial materials, as the four-fold degenerate artificial square spin ice can be mapped to the four-state Potts model. And the new designed model, in which monopoles and topological domain vertices coexist, will exhibit abundant physical connotation. The findings in this project may provide some new designing and modulating methods, enrich the contents of square spin ice model, and further promote the development of artificial spin ice.

人工自旋冰材料是一个新兴崛起并蓬勃发展的研究领域。人工自旋冰的研究一方面让人们对于凝聚态物理中自旋的集体行为和磁单极子这类准粒子激发现象有了更加全面的认识，另一方面让人工激发的磁单极子作为新的媒介进行信息存储、传输以及处理成为可能。本项目关注基态四重简并四方人工自旋冰材料的设计和理论研究，通过格点结构和晶格设计实现对材料的自旋阻挫关系、基态构型和系统磁性的调控；然后利用多种数值模拟方法对新设计的模型的热力学和动力学进行研究，揭示系统中磁单极子的激发和运动的新规律；此外新设计的基态四重简并人工自旋冰可以用四态Potts自旋模型来描述，通过对该人工模型中畴结构的研究，阐明多态Potts模型中的拓扑畴结构激发的丰富物理内涵。本项目的开展，可以提供新的四方人工自旋冰的设计和调控方法，丰富四方人工自旋冰模型的研究内容，进一步促进人工自旋冰材料的发展。

本项目通过对新型人工自旋冰模型的设计研究，以丰富人工自旋冰模型的研究内涵。在执行期间申请人从四方人工自旋冰结构中最基本的磁岛与磁岛之间相互作用入手，给出了人工自旋之间相互作用更精确的算法；并以此为基础提出了基态四重简并的新型四方人工自旋冰模型的设计方案；最后通过与六态POTTS模型等价的三角J1-J2模型对新型四方人工自旋冰模型中存在的拓扑磁畴结构进行研究，解释了拓扑畴的形成及运动规律；此外作为基础研究项目，申请人还对石墨炔-金属材料、MoS2材料等在内的多个二维材料和模型中新颖的物理化学过程进行了探索性研究。项目执行三年来，已达成项目核心目标,并取得了若干阶段性成果。项目资助下共发表基础性研究论文6篇。包括Nano Energy(2)、Applied Surface Science(2)、Jounal of Applied Physics(1)和RSC Advances(1)。在项目资助下共有2位博士生获得了博士学位，3位硕士生获得硕士学位，另有2位硕士生在读。