磁性纳米管的非Stoner-Wohlfarth模型的理论与实验研究

Numerical calculation of magnetic properties is a very effective way to understand the whole magnetic behavior of nanotubes. Currently, the most studies of calculation of magnetic properties of nanotubes are mainly grounded on the Stoner-Wohlfarth (S-W) model, starting from an elongated prolate ellipsoid with single-domain. But, it is hard to imagine how such an ellipsoid is arranged in the hollow tubular structure and hence the realization of predicted magnetic properties has been hindered by the experimental difficulties. Therefore, to investigate the magnetic properties in a more broad geometric range and guide the synthesis of the magnetic nanotubes, an appropriate non S-W model for the calculation of magnetic properties of nanotubes becomes crucially important...Here, based on our previous results on non S-W model, we are willing to study the non S-W model of magnetic nanotubes from the views of theoretical model, experimental synthesis and physical analysis. Through this study, two alternative models of numerical analysis and chain of ellipsoid-rings are proposed to calculate the magnetic properties of nanotubes; two experimental techniques of anodic aluminum oxide-template and electrospinning are employed to synthesize the magnetic nanotubes. By comparing the results between calculation and experiments, we discuss the influence of tubular geometric parameters on the magnetic properties and then prove the usability of non S-W models. Finally, we will clarify the underlying physics of these non S-W models by compared with S-W model. Consequently, our model provides not only a general approach to magnetic nanotubes, but also a new way to explore the functional materials with exotic properties.

作为铁磁学理论中的一个经典模型，Stoner-Wohlfarth（S-W）模型被广泛地应用于磁性纳米颗粒磁性能的理论计算，但基于单磁畴实心椭球体颗粒建立的S-W模型无法描述具有空心管状结构特点的磁性纳米管。因此，构建适合磁性纳米管物理结构特点的非S-W模型是目前该领域的研究热点。基于此，本项目在前期研究基础之上，拟从理论建模、实验求证、物理分析等三个方面对磁性纳米管的非S-W模型进行深入研究。项目研究从理论建模出发，根据磁性纳米管的结构特点，构建微磁学数值分析模型和椭球环链模型，并对其磁学性能进行计算分析；采用多孔阳极氧化铝模板法和静电纺丝法从实验上制备结构参量可调控的磁性纳米管，并通过性能测试求证非S-W模型的合理性；最后通过与S-W模型的对比研究阐述非S-W模型的物理本源，为探索发现具有奇特物理性质的磁性纳米管材料提供理论依据。

当今世界，高科技是衡量一个国家综合实力的重要指标。而要打造高科技材的产品，新材料的制备和研发至关重要。其中一维纳米材料，例如氧化铟纳米线，二氧化锡纳米管，氧化钨纳米棒等，由于其独特的纳米结构呈现出了一系列新颖的物理化学特性，使它们在新器件、新技术等应用方面前景广阔，逐渐成为近年来物理、化学以及材料科学等研究领域的研究热点。特别的，由于低维材料的量子局域效应和表面效应，材料的磁、热、光、电等多功能性（磁传感器、光磁材料、电化学材料等）成为该领域的重要研究方向。基于此，本项目的研究主要获得了以下结果：1）实现了物理法和化学法等多种手段制备一维纳米材料，包括氧化物和金属的纳米管及纳米线。2）阐明了一维结构下材料的能带及态密度的改变及其吸收光谱和荧光光谱的变化规律。3）阐明了一维磁性纳米线的在磁场下的响应关系及变化规律。4）制备了一些列具有优异电化学和光电性能的一维和相关二维材料。