室温铁磁性铁硒-胺杂化半导体纳米材料的可控合成、磁性和电性研究

采用高温有机化学液相法，通过自组装铁硒亚纳米结构和铁胺配体合成新型铁硒-胺杂化磁性半导体纳米材料。研究无机、有机结构单元的组成和微观结构及其界面结构等，对杂化材料的相组成、晶体结构、热稳定性、磁性和电性的影响。归纳具有周期性排列结构的杂化磁性半导体纳米材料的形成规律。结合理论计算、中子衍射、电子顺磁共振和磁测量结果，分析铁硒结构单元的面内磁关联性、磁偶极-偶极相互作用和尺寸效应等，与杂化材料产生长程铁磁有序的关系，阐明室温铁磁性产生机制。根据能带理论模型，分析吸收光谱确定杂化材料的半导体带隙。采用微纳加工技术制备纳米器件，研究杂化纳米材料的电输运与其各向异性层状结构间的关系。分析电流-电压特性、电阻、霍尔电阻等与温度的依赖关系，研究元素掺杂、温度、电场、磁场等对载流子浓度的影响，阐明杂化磁性半导体材料的导电机制。为可控化学合成室温铁磁性无机-有机杂化半导体材料及其未来应用提供科学依据。

This project will study new type ordered inorganic-organic Fe1-xSe-amine hybrid magnetic semiconductors with diverse structures and unique physical and chemical properties. From basic principles of magnetism and formation rule of hybrid materials, new inorganic-organic hybrid magnetic semiconducting materials will be designed based on first-principles calculations. Ordered inorganic-organic hybrid magnetic semiconductors combining inorganic iron selenide fragments and organic amine ligands will be chemically synthesized through a self-assemble way by means of template guiding of amine molecules in optimal chemical solution route. We will emphasize the issue of low magnetic ordering temperatures of hybrid magnetic materials, which limit their potential applications at/above room temperature. The research includes the structures and physical properties, such as microstructure, crystal structure, interface structure, thermal stabilization, growth mechanism, magnetic and electric properties. The focus will be given to the type and chain length of amine molecules, the bonding effect in conjunction of the organic/inorganic components, interface effect, quantum size effect in the magnetic organic-inorganic hybrid semiconducting materials and their influence on the electric structure, band gap, electrical and magnetic properties. The main aim is to explore methods to fabricate novel hybrid magnetic semiconducting materials. The key challenge is to solve physical/chemical issues of the combination of organic and inorganic structural units yielding some new property distinct from the intimate mixture, and to solve some problems for improving the long-range ferromagnetic ordering of inorganic-organic hybrid materials by materials design and optimization. First-principles calculations will be used to analyze the effect of organic ligands on energy band structure of hybrid magnetic materials because of changing the magnetic ionic exchange interactions. The results from first-principles calculations, neutron diffraction and electron paramagnetic resonance spectra will be used to demonstrate the magnetic structure and origin of the magnetism in the hybrid materials. The dependence of current-voltage characteristics, resistance and Hall resistance on temperature will be analyzed. The effects of temperature, electric field and magnetic field on carrier concentration in hybrid semiconductors will be studied, and the conductive mechanism of hybrid semiconductors is clarified. It provides a scientific basis for controllable chemical synthesis of room temperature ferromagnetic inorganic-organic hybrid semiconductor materials and their future applications.