垂直各向异性磁性纳米结构中磁化强度动力学弛豫行为及阻尼特性研究

Nowadays, pursuing the materials with high density, low power, and high speed for spintronic devices is an extremely active area of research interest. In this project, we will focus on the issue of improving writing speed of the ultrahigh density magnetic recording techniques. First, we will fabricate Co/Pt multilayers and FePt thin films and nano-pillar arrays with perpendicular anisotropy. The ferromagnitc resonance (FMR) with variable frequency, temperature, and magnetic field, will be employed to characterize these nanostructures. The magnetization relaxation of these nanostructures will be studied in detail. The relationship between FMR line width and the micro-structure, perpendicular anisotropy, and grain size distribution of these nanostructures will be studied. Furthermore, the relationship of the dipolar interactions and geometry size of these nanostructures will be investigated. The magnetization relaxation processes of these samples will be identified. Based on the micro-magnetic simulations and theoretical analysis, the contribution from spin-flip magnon-electron scattering, the breathing of Fermi surface, and multi-magnon scattering on FMR line width will be discussed in detail. The key issues affecting the damping factor of these nanostructures will be illustrated. Finally, a new approach to control the damping factor will be demonstrated. This project will definitely benefit the scientists on spintronic devices from both experimental and theoretical basis.

高密度、低功耗和高读写速率是目前自旋电子学器件研究的热点内容之一。本项目围绕超高密磁存储中信息高速写入这一核心问题，在掌握制备具有垂直磁各向异性的Co/Pt、FePt磁性纳米单元阵列的工艺基础上，以宽带变温铁磁共振谱仪为主要研究工具，采用变温、变频、及变场等测量方式，详细研究磁性纳米单元阵列的磁化强度动力学弛豫行为及阻尼特性。拟通过改变样品制备条件，调控其各向异性大小、晶粒尺寸与分布、结构、以及取向，探索共振场及其线宽随它们之间的变化规律。进一步通过改变纳米阵列几何尺寸及阵列构型,深入研究垂直各向异性能和静磁相互作用对纳米结构中磁化强度动力学行为的影响。结合微磁学模拟和理论分析，研究各种散射机制、局域及非局域自旋波激发等方式对共振线宽的贡献，获得磁化强度动力学弛豫及能量耗散机理，揭示影响阻尼因子的关键因素，从而掌握调控阻尼因子的有效手段。本课题将为研究新型自旋电子学器件提供实验和理论依据。

高密度、低功耗和高读写速率是目前自旋电子学器件研究的热点内容之一。我们围绕超高密磁存储中信息高速写入这一核心问题，在掌握制备具有垂直磁各向异性的Co/Pt、FePt磁性纳米单元阵列的工艺基础上，以宽带变温铁磁共振谱仪为主要研究工具，采用变温、变频、及变场等测量方式，详细研究了磁性纳米单元阵列的磁化强度动力学弛豫行为及阻尼特性。通过改变样品制备条件，调控其各向异性大小、晶粒尺寸与分布、结构、以及取向，探索了共振场及其线宽随它们之间的变化规律。进一步通过改变纳米阵列几何尺寸及阵列构型,深入研究了垂直各向异性能和静磁相互作用对纳米结构中磁化强度动力学行为的影响。我们还结合微磁学模拟和理论分析，研究各种散射机制、局域及非局域自旋波激发等方式对共振线宽的贡献，获得了磁化强度动力学弛豫及能量耗散机理，揭示了影响阻尼因子的关键因素，从而掌握了调控阻尼因子的有效手段。这些结果为研究新型自旋电子学器件提供实验和理论依据。