正电子湮没谱学理论与技术研究稀磁半导体中磁性起源及磁耦合机制

稀磁半导体（DMSs）作为自旋电子学器件的核心材料融合了半导体和铁磁特性，研究其磁性起源及微观磁耦合机制成为材料科学和信息技术领域前沿热点。本课题依托国家重点实验室的正电子装置平台，利用先进的正电子湮没技术能够灵敏观察材料微观结构和点缺陷的独特优势，深入分析某些DMSs中磁性和微结构之间的关系，d0磁性的起源，以及缺陷对过渡金属离子之间磁耦合的影响等问题。在实验上发展高效率的正电子湮没寿命-动量关联谱仪，研究正电子在稀磁半导体中的湮没行为。在理论上基于密度泛函的第一性原理计算以及正电子理论计算软件计算不同掺杂和缺陷条件下微观体系的磁矩及自旋密度分布，研究DMSs的磁耦合机制，并对半导体缺陷在不同条件下的磁耦合机制给出深入的见解。本课题将通过正电子实验研究和磁性理论计算相结合给出清晰的稀磁半导体材料微观磁结构图像，为自旋电子学器件研发以及未来信息技术发展提供理论和实验的基础。

Dilute magnetic semiconductors (DMSs) have attracted increasing attention in the past decade because of their promising technological applications in the ?eld of spintronics. A lot of groups focus their efforts on the topic of magnetic origin, while no agreed mechanism of observed ferromagnetism (FM) was established clearly. This topic will rigorously analyze the relationship between the magnetic properties and microstructures in some of DMSs by using positron annihilation spectroscopy, which was proved to be a sensitive tool for study of microstructures and defects in materials. Based on the positron facilities in the State Key Laboratory of Particle Detection and Electronics of China, we will study the magnetic mechanisms in DMSs, including origin of D0 magnetism, defect-induced FM, and the effect of microstructures on the coupling between magnetic ions. Besides, we will develop efficient Positron Age-momentum Correlation spectrometer (AMOC) to demonstrate the annihilation behavior of positrons in DMSs. Moreover, the first-principle calculation and positron theoretical calculation also will be developed to study the spin-density states and magnetic interaction in different magnetic microstructures. We will try to give original insight in magnetic origin and coupling mechanism in different magnetic systems。Research on this topic will provide theoretical basis for spintronics application and benefit the development of information technology in the future.