Investigating the Effects of Charge Carrier Modulation in the Development of Ferromagnetic Order in Semiconducting Oxides

****非技术摘要****磁力是人类已知的最古老的现象之一，也是最难理解的现象之一。磁性材料通常由镍或钴等金属离子制成，已被人们所知并使用了几个世纪。该项目将进行一系列实验，以测试本身不具有磁性的材料中是否会产生磁性。这一目标将通过引入原子级点缺陷来修改氧基半导体来实现，特别是在氧原子的有序网络中制造孔洞。这些缺陷预计会导致这些氧化物半导体的电导率增加，从而引发铁磁性的发展。成像和分析技术的结合，移动电子、电门控和光学激发之间的相互作用，将被用来阐明磁性在这些半导体系统中是如何发展的。该奖项将极大地促进对金属和绝缘体中间材料中铁磁性如何发展的基本理解，并为制造可用于高级计算的新型磁存储器和逻辑器件的材料提供重要的见解。参与该项目的学生将接受适用于半导体/纳米技术行业以及学术界职业的先进分析技术的培训。 ****技术摘要****该项目将进行一系列实验，以测试为开发半导体过渡金属氧化物中的室温铁磁性而提出的多种机制，合理化介于局部矩磁性和巡回磁性之间的材料的性能。这些特性包括局域矩、移动电荷载流子和点缺陷（特别是氧空位）之间的相互作用。 这将通过将缺氧氧化物半导体中电导率的增加与铁磁性的发展相关联来实现。使用成像和分析技术的独特组合，预计可以阐明载流子浓度的变化如何随着非磁性离子和点缺陷、电选通和光学激发的变化而影响这些磁性，以及过渡金属的局部矩如何与氧空位相互作用以诱导铁磁性。该奖项将通过以受控方式探测绝缘体和导体之间的系统中的磁性，极大地增进对铁磁性的基本理解。两位博士。参与该项目的学生和多名本科生将接受适用于半导体/纳米技术行业以及学术界职业的先进分析技术的培训。

****NON-TECHNICAL ABSTRACT****Magnetism is one of the oldest phenomena known to men, yet one of the most difficult to understand. Magnetic materials, typically made from metallic ions such as nickel or cobalt, have been known and used for centuries. This project will pursue a series of experiments to test whether magnetism can arise in materials where none of the constituents are magnetic by themselves. This goal will be pursued by modifying oxygen-based semiconductors through the introduction of atomic scale point defects, specifically making holes in the ordered network of oxygen atoms. These defects are expected to lead to an increase in the electrical conductivity of these oxide semiconductors, which can trigger the development of ferromagnetism. A combination of imaging and analytical techniques, the interplay among mobile electrons, electrical gating, and optical excitations, will be used to elucidate how magnetism develops in these semiconducting systems. This award will substantially advance the fundamental understanding of how ferromagnetism develops in materials that are intermediate between metals and insulators as well as provide important insight into materials for making new magnetic memory and logic devices, which could be used for advanced computing. The students participating in this project will be trained in advanced analytical techniques applicable to careers in the semiconductor/nanotechnology industries, as well as in academia. ****TECHNICAL ABSTRACT****This project will pursue a series of experiments to test a number of mechanisms that have been proposed for the development of room temperature ferromagnetism in semiconducting transition metal oxides, rationalizing the properties of materials intermediate between local moment magnetism and itinerant magnetism. These properties include the interplay between localized moments, mobile charge carriers, and point defects, specifically oxygen vacancies. This will be accomplished by correlating the emergence of an increased electrical conductivity in oxygen deficient oxide semiconductors with the development of ferromagnetism. Using a unique combination of imaging and analytical techniques it is expected to be possible to elucidate how the shift in carrier concentration with the inclusion of non-magnetic ions and point defects, electrical gating, and optical excitations affects these magnetic properties and how local moments from transition metals interact with the oxygen vacancy to induce ferromagnetism. This award will substantially advance the fundamental understanding of ferromagnetism by probing in a controlled manner the magnetism in systems intermediate between insulators and conductors. The two Ph.D. students and multiple undergraduates participating in this project will be trained in advanced analytical techniques applicable to careers in the semiconductor/nanotechnology industries, as well as in academia.