几何阻挫磁体AB2O4体系中无序诱发自旋玻璃相变的研究

项目名称： 几何阻挫磁体AB2O4体系中无序诱发自旋玻璃相变的研究

项目编号： No.11204270

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学I

项目作者： 应耀

作者单位： 浙江工业大学

项目金额： 30万元

中文摘要： 几何阻挫磁体中自旋玻璃行为的形成机制一直没有得到澄清和理解。本项目基于几何阻挫磁体AB2O4体系中典型的ZnCr2O4，通过掺杂离子半径相近的非磁性和磁性离子方式分别在几何阻挫磁体体系中引入离子稀释无序和交换作用无序。利用先进的人工智能可控气氛炉制备高质量的样品。设计磁性测量实验，利用磁性测量系统（MPMS），测量样品的直流和交流磁性行为，研究体系的磁结构和自旋弛豫现象，并借助临界幂等理论模型研究几何阻挫磁体AB2O4体系中自旋玻璃的自旋动力学，阐明两种无序诱发自旋玻璃的机制。通过掺杂半径差异较大的离子，改变其晶格结构，进一步研究自旋-晶格耦合对自旋玻璃形成的影响。在以上研究的基础上，澄清几何阻挫磁体中自旋玻璃与传统的自旋玻璃是否有差异。

中文关键词： 几何阻挫磁体；自旋玻璃；铁氧体体系；磁结构；

英文摘要： The origin of spin glass in geometrically frustrated magnets is still unknown and needs to be clarified. ZnCr2O4, as a typical material in geometrically frustrated magnets of AB2O4, is employed in this project. The ionic diluted disorder and the exchange-interaction disorder (bond disorder) are introduced by doping the nonmagnetic and magnetic ions with similar radii in ZnCr2O4, respectively. Advanced artificial intelligence atmosphere-controllable furnace is used to synthesize the high-quality sample. The designed magnetic experiments are carried out in magnetic properties measurement system (MPMS). The dc and ac magnetic properties are measured to investigate the detailed magnetic structure and spin relaxation of system. The theoretical models, such as critical-power law and so on, are employed to study the spin dynamics of spin glass in geometrially frustrated magnets. Then, the project clarifies the machanism of spin glass induced by these two disorders. Through doping the ions with appropriately different radii in ZnCr2O4, the lattices are changed to study the influence of spin-lattice coupling on the formation of spin glass. Finally, the project clarifies whether there is the difference between spin glass in geometrically frustrated magnets and conventional spin glass.

英文关键词： geometrically-frustrated magnet；spin glass；ferrite system；magnetic structure；