铁磁与顺磁金属中的纯自旋流输运研究

项目名称： 铁磁与顺磁金属中的纯自旋流输运研究

项目编号： No.51471081

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 范小龙

作者单位： 兰州大学

项目金额： 85万元

中文摘要： 自旋霍尔效应是实现自旋流产生与探测的理论依据。由于自旋霍尔角是描述材料内部自旋流与电荷流之间转化效率的核心参数，所以获得具有大自旋霍尔角的材料是实现自旋流技术功能化的基础。但是这一关键参数到目前仍无法准确测量。本项目拟采用非线性自旋动力学原理结合独特的器件设计，首先解决自旋霍尔角准确测量这一关键科学问题；其次按照本征（单质）与非本征（杂质、缺陷和表面处的散射）自旋霍尔效应起源为理论基础，以人为控制非本征因素作为增大自旋霍尔角的主要技术途径，在自身自旋轨道较强的5d过渡族金属元素中寻找高自旋霍尔角的单质或合金体系。目标是1）建立自旋霍尔角的准确测量原理与技术，2）寻找自旋霍尔角大于0.1的材料体系。该研究不仅可以建立自旋霍尔角的准确测试方法，为相关材料研究提供技术保障，而且在获得高自旋霍尔效应材料体系的同时掌握这一关键参数的调控技术，从材料研究的角度推动自旋流技术在实际应用上的发展。

中文关键词： 自旋电子学；磁性薄膜；磁电阻效应；自旋动力学；自旋相关输运

英文摘要： Spintronic devices manipulating pure spin currents, flows of spin angular momentum without charge current, should play an important role in low energy consumption electronics of the next generation. Therefore, the methods for producing and manipulating pure spin current have recently attracted much attention. The Spin Hall Angle (SHA), which is given by the ratio of spin hall and charge conductivity, is a quantified parameter to describe the effectiveness of this spin-charge conversion. The usual methods to determine SHA, however, have critical defects, so that the experimentally reported values are quite different for nominally identical materials, even for similar methods utilizing spin pumping. In such a situation, the correct measurement of the SHA has been the most fundamental issue for studying spin current and the relevant materials. What we propose here, is to establish a new method to fix this critical problem. By using CoZr magnetic film to pump spin current into the nonmagnetic metal layer, the measured longitudinal voltage would be the pure inverse spin hall effect due to spin pumping. The reason is caused by the fact that the CoZr show quite weak anisotropic magnetoresistance, but with moderate anomalous hall effect, which can be used for determining the amplitude of the pure spin current when FMR happens. By doing that, we can build a correct measurement of the SHA. Moreover, we will systematically study the spin hall angle in 5d transition metals based materials. We will try to obtain the specific composition and condition for those materials with SHA as large as possible, and to find the reasonable approaches to further enhance spin hall effect in metals.

英文关键词： spintronics;magnetic films;magnetoresistance;spin dynamic;spin related transpotation