富勒烯过渡金属化合物薄膜的磁性以及在自旋电子学上的应用

Organic spintronics is an important subject of spintronics. Fullerene is a hot materials in this area as an organic spintronics material that can show magnetoresistance at room temperature. However, the mechanism of generating the magnetoresistance is to be explored yet. It is reported that, in a sandwich junction consisted by Co and fullerene, the Co atom can penetrate into the fullerene layer. However, there is no inverstigation on what effect such penetration shows on the transport properties of the system. As a first attempt to answer this question, this project plans to systematically investigate the monolayer of transion metal fulleride on ferromagnetic metal surface. We are going to lock the adsorption structures with first-principle method and calculate the electronic structure, exchange coupling, magnetocrystalline anisotropy, the onsite Coulomb repulsion, the hopping integral and the magnetoresistance of the corresponding sandwich junction. We are gong to calculate the response to the external field and temperature dependent properties by Monte Carlo and Landau-Lifshitz-Gilbert equations. By comaring with the experiments, the role of the penetrating transition atom play on the transport properties can be decided. And the manipulating method of the system can be suggested. This project will serve as a theoretical fundation for the development of the novel devices of spintronics.

有机自旋电子学是自旋电子学的重要方向之一。富勒烯作为少数能在室温表现出磁阻效应的有机自旋电子学材料而成为这一领域的研究热点。然而，其产生磁阻的机理目前尚有待探索。有报道称，富勒烯和钴组成的三明治结中，钴会渗入富勒烯层中。而这种渗入对体系的输运性质的影响亟待研究。本项目计划系统性的研究富勒烯和过渡金属在铁磁金属表面共吸附形成的单层膜，通过第一性原理的方式确定吸附结构并计算对应的电子结构、交换耦合常数、磁晶各向异性能、在位库伦排斥，跳跃积分以及对应三明治结的磁阻；通过经典蒙特卡洛和朗道-栗弗席兹-吉尔伯特方程的模拟，计算体系对外场的响应以及温度相关的性质。通过和相关实验的对比，给出过渡金属原子的渗入对富勒烯薄膜输运性质的影响以及探索相关体系的调控手段。本项目将为新型有机自旋电子器件的发展奠定理论基础。

本项目开始计划研究富勒烯中金属离子的磁学性质，但后来发现预设方向有误，因此调整了研究方向。分别研究了二硫化钼和硫化钴对一氧化氮的响应，以及富勒烯在Fe(100)上的生长和磺酸钴的摩擦生电特性。研究发现。一氧化氮的能级和二硫化钼之间能形成特殊的排列，从而形成有效的n掺杂来改变硫化钼的电导。而硫化钴能提供强的吸附。两者结合可以构成气敏性能优良的材料。富勒烯由于其内部结构，在不同的外界条件下有不同的生长机制。磺酸钴中分离的价带顶和导带底以及片段之间的弱相互作用使其是一种优良的摩擦电极材料。