【作者】 袁立；

【导师】 赵振杰；

【作者基本信息】 华东师范大学 ， 凝聚态物理， 2008， 硕士

【摘要】 巨磁阻抗(Giant Magneto-impedance,简称GMI)效应指的是铁磁材料的交流阻抗值随着外加磁场的变化会发生较大变化的现象。由于具有灵敏度高,响应快,能耗低等很多优点,所以在磁传感器和磁记录上有着非常广泛的应用前景。本文简要回顾了非晶玻璃包裹丝和巨磁阻抗效应的发展历史和研究现状,采用高频感应加热熔融快淬拉引法制备出了钴基非晶玻璃包裹丝,并研究了电流应力退火的条件对Co基非晶丝软磁性能的影响,也研究了空气退火对Co基非晶丝的软磁性能以及非对称性GMI效应的影响。论文的主要内容包括:1用感应加热熔融快淬拉引法制备出Co基非晶玻璃包裹丝,并对褪玻璃后的丝进行电流和电流应力退火。(1)钴基非晶玻璃包裹丝在褪掉玻璃后软磁性能会有所上升。(2)当电流密度和应力分别小于2.0×10~7A/m~2和90MPa时,随着电流密度和应力的增大,样品的软磁性能会有所改善,在2.0×10~7A/m~2和90MPa时达到最好,电流密度和应力继续加大,软磁性能又会下降。2在褪玻璃包裹的基础上对丝进行暴露在空气当中的火炉退火。(1)研究了暴露在空气中火炉退火的样品与温度和时间的关系。结果显示样品的GMI效应相对于磁场的敏感度随着温度的升高和时间的加长是先增强后减弱。在温度低于400℃和时间小于9h时,随着温度的上升和时间增长,样品的软磁性能慢慢变好,温度超过400℃、时间超过9h,软磁性能迅速下降。(2)GMI效应的非对称性和在空气中退火后样品的软磁性能改善的主要原因是丝表面的氧化层与纳米晶芯层之间的耦合相互作用。更多还原

【Abstract】 The giant magneto-impedance (GMI) effect is a phenomenon that there will be a giant change of the impedance of a ferromagnetic material when it is subjected to an external magnetic field. There are a lot of prospective applications (for example, in magnetic recording heads and sensor elements) because of its many advantages (high-sensitivity、quick response and low power consumption, and so on).A summary of research on GMI effect is generally presented in this thesis. Amorphous Co-based microwires are prepared by Taylor-Ulitovsky method. Different annealing methods are used to improve their properties. We study the soft magnetic properties and the asymmetrical GMI effect on annealing conditions and the exchange coupling between oxidation surface and nanocrystalline core.The main content is listed below:1. Preparation of Amorphous Co-based glass-covered microwires and these materials are preformed by Joule current and stress Joule annealing.(1) The soft magnetic properties would be improved after removal of the glass cover.(2) The optimal density of the Joule current is 2.0×10~7 A/m~2 and the best stress is 90 MPa. The soft magnetic properties improve with the increase of the density of current and the intensity of the stress if the density and stress are less than 2.0×10~7 A/m~2 and 90 MPa, then decease when current and stress continue to increase.2. Amorphous Co-based microwires are annealed in open air after glass coating remove.(1) The relationship between giant magneto-impedance effect and the annealing temperature and time is investigated. The results show that the sensitivity of GMI effect to magnetic field firstly increases then decreases with the annealing temperature and time. The maximum of GMI sensitivity was obtained in the samples annealed at 400℃for 9 hours.(2) It is realized that the exchange coupling interaction is the main reason of the AGMI and the improvement of soft magnetic properties of the wires.更多还原