一维纳米结构的制备以及磁性的理论和实验的研究

发布时间：2018-05-20 00:43

本文选题：一维结构 + 自组装　；参考：《东南大学》2015年硕士论文

【摘要】：最近十几年以来,由于磁性一维(1D)纳米材料具有一些特异的物理、化学性质,使得其在磁存储器件、自旋电子器件方面具有极大的应用潜力,同时磁性一维纳米结构易有序操纵,易建立理论模型具有重要的科学研究意义,已经引起广泛关注。特别是一维磁性纳米结构相关技术得到了迅速的发展,先后开发出来了各种各样的制备方法,例如自组装方法、电子束或离子束刻蚀方法等。本论文以两种一维磁性纳米结构作为研究对象,一维紧缩的坡莫合金纳米线和一维自组装的Fe304颗粒链,分别在理论和实验上对其磁输运相关的性质,得到主要结果如下：1、针对自旋电子学中新效应电流驱动畴壁位移和弹道巨磁电阻效应的研究背景,选择坡莫合金构成的纳米紧缩器件为研究对象,研究了不同紧缩器件的自旋的分布和磁畴壁的形成条件。(1)通过电子束曝光的方法,采用2次曝光的技术成功地制备了渐变的紧缩的纳米线器件。在规避了电子的近邻作用,采用设计尺寸和曝光剂量达到了不同尺寸的纳米点接触宽点。(2)研究发现畴壁形成和点接触宽度相关,在80nmm的点接触宽度下成功的观察到紧缩的纳米线点接触处捕捉到的形态简单而尖锐的磁畴壁,当宽度变为260nm时,点接触处自旋呈现单畴结构。(3)采用微磁学软件,以寻找在突变的紧缩纳米线中心产生磁畴壁的几何尺寸为目标,研究了在紧缩纳米线中心处形成的条件及其规律。为实验研究提供了指导。2、在KNO3氧化Fe(OH)2凝胶的法制备的过程中,通过外加合成诱导磁场我们成功实现了Fe304链状结构在磁场诱导下的自组装,通过调节外磁场的强度和添加乙二醇实现了不同长径比的调控。借助外加排列磁场的诱导成功地将颗粒链在硅片上有序的排列。对颗粒链的结构和磁性的系统研究的结果如下：(1)结合XRD和Raman测量结果,确定样品是纯相的Fe3O4,通过磁滞回线对一维Fe3O4颗粒链进行了磁性研究,显示了一维Fe3O4颗粒链具有明显的形状磁各向异性,并且颗粒链的形状磁各向异性随着合成磁场的增加而增大。由XMCD测量,发现B位上的Fe2+和Fe3+的比例随着诱导磁场的变化而发生变化。推测原因可能是外加的合成磁场的影响。(2)首次成功制备了单根一维Fe304颗粒链器件,并对其输运性质进行了研究。发现电流在210μA处有大幅度的电阻突变,电阻率从1.29×10-4Ωm变到0.96×10-4Ωm,我们认为是颗粒间形成的畴壁,当电流推动了畴壁的运动导致的自旋角动量转移所致。同步辐射XPEEM对磁畴的测量以及微磁学模拟成功的证明了我们的推断。(3)实验发现颗粒链中颗粒间磁化方向不同并交错分布,在有些磁化方向相反的颗粒接触处存在畴壁,畴壁的位置具有不确定性。当颗粒链并排距离很近时存在磁相互作用导致并排的两个颗粒自旋相反。(4)我们对Fe304单磁性球颗粒链和双排磁性球颗粒链分别在零磁场以及剩磁状态下磁矩分布进行了计算,并统计了每种情况下畴壁出现率。证实了畴壁会出现在两颗粒接触的位置,对实验结果做出了较为成功的拟合。
[Abstract]:Because of the specific physical and chemical properties of magnetic one-dimensional (1D) nanomaterials in the last decade, it has great potential in magnetic storage devices and spintronic devices. At the same time, magnetic one-dimensional nanostructures are easily manipulated and easy to establish a theoretical model. In particular, one dimensional magnetic nanostructure related technology has developed rapidly, and a variety of preparation methods have been developed, such as self assembly, electron beam or ion beam etching. Two one-dimensional magnetic nanostructures are used as research objects, one dimensional compact permalloy nanowires and one dimensional self-assembly. The main results are as follows: 1. 1, for the research background of the domain wall displacement and the ballistic giant magnetoresistance effect of the new effect current driving in spintronics, the nano austerity components made up of permalloy are selected as the research object, and the self constrictive devices are studied. The distribution of the spin and the forming conditions of the magnetic domain wall. (1) by the method of electron beam exposure, the tapered nanowire devices are successfully prepared by 2 exposure techniques. The contact width of different sizes of nanowires is achieved by the design dimension and exposure dose. (2) the study of domain wall formation and points has been found. The contact width is related, and at the point contact width of the 80nmm, the simple and sharp magnetic domain wall captured by the compact nanowire contact is observed. When the width becomes 260nm, the spin of the point contact presents a single domain structure. (3) the micromagnetic software is used to find the geometric ruler of the magnetic domain wall at the center of the abrupt compact nanowire. As a target, the conditions and laws of the compact nanowire center are studied. The experimental research provides guidance.2. During the preparation of the KNO3 oxidation Fe (OH) 2 gel, we successfully realized the self-assembly of the Fe304 chain structure under the magnetic field by adding the induction magnetic field, by adjusting the intensity and addition of the external magnetic field. Ethylene glycol realized the regulation of different length to diameter ratio. The structure and magnetic properties of particle chains were studied in order by the induction of magnetic field. The results of the structure and magnetic properties of the particle chain are as follows: (1) it is determined that the sample is the Fe3O4 of pure phase with the results of XRD and Raman, and the one-dimensional Fe3O4 particle chain is carried out by the hysteresis loop. The magnetic anisotropy of the one-dimensional Fe3O4 particle chain has obvious shape and magnetic anisotropy, and the shape and magnetic anisotropy of the particle chain increases with the increase of the synthetic magnetic field. The proportion of Fe2+ and Fe3+ on the B position changes with the change of the induced magnetic field. The reason may be the addition of the synthetic magnetic field. (2) a single one-dimensional Fe304 particle chain device was successfully prepared for the first time and its transport properties were studied. It was found that the current has a large amplitude resistance mutation at 210 Mu and the resistivity changes from 1.29 x 10-4 Omega m to 0.96 x 10-4 Omega m. We think it is a domain wall formed between particles, when the electric current drives the spin angular momentum transfer caused by the motion of the domain wall. It is caused by the measurement of magnetic domain and the success of the micromagnetic simulation of XPEEM. (3) the experiment found that the direction of magnetization between particles in the particle chain is different and interlaced, and there is domain wall in the contact of some particles with opposite direction of magnetization, and the position of the domain wall is uncertain. The magnetic interaction leads to the opposite two particles spin in parallel. (4) we calculate the magnetic moment distribution of the Fe304 single magnetic particle chain and the double row magnetic ball particle chain in the zero magnetic field and the remanence state respectively, and statistics the appearance rate of the domain wall in each case. It is proved that the domain wall will appear in the position of the two particle contact and the experimental results. A more successful fitting is made.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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