基于极化中子反射技术的CoFe/IrMn双层膜的自旋结构研究

项目名称： 基于极化中子反射技术的CoFe/IrMn双层膜的自旋结构研究

项目编号： No.11505163

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 任建坤

作者单位： 中国工程物理研究院核物理与化学研究所

项目金额： 23万元

中文摘要： 影响自旋阀和磁性隧道结性能的关键因素之一是反铁磁性薄膜通过交换偏置耦合对铁磁薄膜的钉扎效果。铁磁层(FM)/反铁磁层(AFM)双层膜的交换偏置效应强烈依赖组成层的铁磁层和反铁磁层厚度、自旋结构及界面结构等微观结构参数。因此，精确获取FM/AFM双层膜的微观结构非常重要。极化中子反射技术是表征磁性（自旋）结构随深度变化的强有力工具，本项目旨在利用极化中子反射技术表征CoFe/IrMn双层膜磁性（自旋）结构，从而获得精确的界面自旋结构及AFM体自旋结构。结合振动样品磁强计测试磁滞回线，分析不同IrMn厚度、界面粗糙度及扩散层厚度等微观结构对交换偏置和矫顽力的影响。同时结合理论计算，综合分析CoFe/IrMn反铁磁层厚度对交换偏置和矫顽力及磁性（自旋）结构的影响，揭示交换偏置场与双层薄膜自旋结构的关联，研究其内在物理机制。

中文关键词： 中子散射；极化中子反射技术；自旋结构；交换偏置；磁畴结构

英文摘要： The key to the performance of spin valves and magnetic tunnel junctions is the pinning of a ferromagnetic (FM) layer by exchange biasing of an antiferromagnetic (AF) layer. Interfacial exchange bias effects of FM/AFM bilayer strongly depend on the thicknesses, interfacial structures and spin structures etc. of the constituent layers. Thus, determining the bilayer magnetic structures (i.e. spin structures) is extremely important. Polarized neutron reflectometry is a powerful tool for investigating the magnetization profiles of FM&AFM bilayers; it is well suited to probe the magnetic structure of FM/AFM bilayers during the magnetization reversal. In this project, we plan to prepare CoFe/IrMn bilayers with facility for DC-magnetron-sputtering, utilize Vibrating Sample Magnetometer (VSM) to measure hysteresis loops, from which HE&HC can be determined, and analyze the effects of different IrMn thicknesses and interfacial roughness on exchange bias (HE) and coercivity (HC); The FM/AFM interfacial and AFM bulk magnetic structures will be determined through polarized neutron reflectometry, the relationship between magnetic structures and exchange bias effects will be revealed. All experiments results (including IrMn thicknesses, HE&HC, magnetization profiles etc.) will be combined to find general properties of the exchange bias systems with different thicknesses of IrMn and diffusion layers, interfacial roughness and magnetic or spin structures and to reveal the inherent physical mechanism.

英文关键词： neutron scattering;polarized neutron reflectometry;spin structure;exchange bias;magnetic domain structure