Materials World Network: Magnetic Nanostructures with Perpendicular Anisotropy

材料世界网络项目旨在研究具有垂直各向异性的磁性纳米结构，这种结构具有迷人的磁化反转机制，并在磁记录和自旋电子学中具有重要的技术应用。该网络将协调美国加州大学戴维斯分校(UCD)和美国国家标准与技术研究所(NIST)以及台湾国立清华大学(NTHU)的研究小组，具有互补的专业知识和背景。对具有均匀和/或梯度垂直各向异性的纳米结构进行系统的研究，以探索其随深度变化的磁组态和各向异性梯度，研究基本的磁化反转机制和动力学，并考察降低晶间交换耦合的效果。样品将由UCD和NTHU的研究人员协同努力合成，包括连续薄膜、颗粒分离颗粒膜、纳米点和纳米线。对于均匀各向异性纳米结构，我们将研究与尺寸相关的磁化反转机制和微观磁记忆效应；通过使用中间层来探索原型垂直介质中磁各向异性和颗粒偏析的同时增强。对于梯度各向异性纳米结构，NIST将进行偏振中子反射仪(PNR)研究，以直接和定量地测量随深度变化的磁化强度分布和各向异性梯度。具有自旋极化分析的扫描电子显微镜(SEMPA)将在NIST上用于成像矢量磁化作为研磨深度的函数；它将探测这些材料中被预测为促进可写入性和热稳定性的域壁辅助反转。该奖项由材料研究部和国际科学与工程办公室共同资助。了解和控制垂直各向异性磁性纳米结构中的磁化反转机制将具有深远的技术影响。所研究的纳米结构在垂直磁记录、梯度磁介质、磁随机存取存储器和其他类型的自旋电子器件中具有重要的应用。该项目汇集了来自物理和材料科学的研究人员网络，他们在纳米结构合成、探针显微镜、磁和磁光表征以及中子和X射线散射方面具有专业知识。这一配置非常适合于促进该项目的所有科学方面。国际合作是这个项目的核心。一个关键组成部分是国际互访，这将促进执行关键实验、加强对结果的讨论和规划未来工作。南洋理工大学和南洋理工大学的学生将参观对方的S实验室，整合研究工作，参与实验，获得国家科学技术研究所和先进光源公司的知识和培训，学习涵盖研究方方面面的全面技术，并获得宝贵的文化经验。

This Materials World Network project aims at investigating magnetic nanostructures with perpendicular anisotropy, which have fascinating magnetization reversal mechanisms and important technological applications in magnetic recording and spintronics. The network will coordinate research groups at the University of California-Davis (UCD) and National Institute of Standards and Technology (NIST) in the US, and the National Tsing Hua University (NTHU) in Taiwan, with complementary expertise and backgrounds. Systematic studies will be carried out on nanostructures with uniform and/or graded perpendicular anisotropy to probe their depth-dependent magnetic configurations and anisotropy gradient, to study the basic magnetization reversal mechanisms and dynamics, and to examine the effect of decreasing inter-grain exchange coupling. Samples will be synthesized in coordinated efforts by the UCD and NTHU researchers, including continuous thin films, grain-segregated granular films, nanodots and nanowires. For uniform anisotropy nanostructures, the size-dependent magnetization reversal mechanisms and microscopic magnetic memory effects will be studied; simultaneous enhancements of magnetic anisotropy and grain segregation in prototype perpendicular media will be explored by using an intermediate layer. For graded anisotropy nanostructures, polarized neutron reflectometry (PNR) study will be performed at NIST to directly and quantitatively measure the depth-dependent magnetization profile and anisotropy gradient. Scanning electron microscopy with spin polarization analysis (SEMPA) will be used at NIST to image vector magnetization as a function of milling depth; it will probe domain wall assisted reversal in these materials that has been predicted to facilitate both writability and thermal stability.This award is co-funded by the Division of Materials Research and the Office of International Science and Engineering.Understanding and controlling the magnetization reversal mechanisms in magnetic nanostructures with perpendicular anisotropy will have profound technological impacts. The nanostructures under investigation have important applications in perpendicular magnetic recording, graded magnetic media, magnetic random access memory, and other types of spintronic devices. The project brings together a network of researchers from physics and materials science with expertise in synthesis of nanostructures, probe microscopy, magnetic and magneto-optical characterization, and neutron and x-ray scattering. This configuration is ideally suited to promote the project in all its scientific aspects. International collaboration is at the heart of this project. A critical component is the international exchange visits, which will facilitate executions of key experiments, enhance discussions of results and planning of future work. UCD and NTHU students involved will visit each other?s lab, integrate the research efforts, participate in experiments, acquire knowledge and training at NIST and Advanced Light Source, learn the comprehensive set of techniques covering all aspects of the research, and gain valuable cultural experiences.