Synthesis of Magnetic Cr-Based Chalcogenide Spinels: From Nanocrystals to Thin Films

阿拉巴马大学的阿鲁纳瓦·古普塔教授正在接受大分子、超分子和纳米化学计划的奖励，以研究新的低温路线，涉及溶液化学和化学气相沉积方法，用于合成和表征一类有前景的铬基磁石尖晶石材料。这些材料以单分散纳米晶和薄膜的形式合成，将使用先进的分析技术进行表征，并详细研究它们的物理性质。该计划的动机是研究人员获得的理论结果，这些结果表明在一些混合的铜、镉球晶中诱导半金属性的可能性令人兴奋--即一种材料，在费米能级的一个自旋带中有间隙，而在另一个自旋带中没有间隙。这项研究的智力价值在于利用创新的合成和表征方法合成和研究新型混合脉石，这些方法有可能实现一类新的自旋电子材料。在将并行进行的带结构计算的指导下，还将尝试合成其他取代的脉石系统。与橡树岭国家实验室合作，将利用具有原子序数对比(STEM-Z)表征技术的超高分辨率扫描电子显微镜对纳米晶体和薄膜进行详细的结构表征。项目人员将在与拟议研究有关的几个正在进行的教育和外联活动中发挥关键作用。这些措施包括与当地学校合作，促进高中生参与研究、公共旅游和示范。阿拉巴马大学的阿鲁纳瓦·古普塔教授得到化学系大分子、超分子和纳米化学计划的支持，研究一类复杂的硫和硒基无机材料-被称为ChalcSpinels-显示出新的磁性。作为研究的一部分，PI和他的学生将利用独特的溶液化学和气相沉积方法来控制这些材料的纳米晶体和薄膜的合成。特别令人感兴趣的是一些混合的球晶石尖晶石，理论上预测它们属于一小类被称为半金属的奇异材料。半金属材料被认为是自旋电子学研究的“圣杯”之一，而且仍然难以捉摸。这项研究将通过认识到这类到目前为止还没有被充分开发的极其有趣的材料的潜力，来帮助维持和增加自旋电子学这个年轻领域的势头。该项目需要多学科的努力，这将对科学知识、教育、外联和基础设施做出重大贡献。项目人员将在与拟议研究有关的几个正在进行的教育和外联活动中发挥关键作用。这些措施包括与当地学校合作，促进高中生参与研究、公共旅游和示范。

Professor Arunava Gupta of the University of Alabama is receiving an award from the Macromolecular, Supramolecular and Nanochemistry Program to investigate novel low temperature routes, involving solution chemistry and chemical vapor deposition methods, for the synthesis and characterization of a promising class of magnetic Cr-based chalcospinel materials. These materials, synthesized in the form of monodisperse nanocrystals and thin films, will be characterized using advanced analytical techniques and their physical properties studied in detail. The program is motivated by theoretical results obtained by the investigator that suggest the exciting possibility of inducing half-metallicity - i.e., a material in which there is a gap in one spin band at the Fermi level and no gap in the other spin band - in some of the mixed Cu,Cd chalcospinels. The intellectual merit of the research lies in the synthesis and investigation of the novel mixed chalcospinels utilizing innovative synthesis and characterization methods that have the potential for realizing a new class of spintronic materials. Guided by band structure calculations that will be conducted in parallel, the synthesis of other substituted chalcospinel systems will also be attempted. In collaboration with Oak Ridge National Laboratory, ultra high-resolution scanning transmission electron microscopy with atomic number contrast (STEM-Z) characterization technique will be utilized for detailed structural characterization of the nanocrystals and thin films. Project personnel will play a key role in several ongoing education and outreach activities related to the proposed research. These include collaboration with local schools to facilitate participation by high school students in research, public tours and demonstrations. Professor Arunava Gupta of the University of Alabama is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry to investigate a class of complex sulfur and selenium-based inorganic materials - referred to as chalcospinels - that display novel magnetic properties. As part of the research, the PI and his students will utilize unique solution chemistry and vapor deposition approaches for the controlled synthesis of nanocrystals and thin films of these materials. Of particular interest are some mixed chalcospinels, which are theoretically predicted to belong to a small class of exotic materials called half-metals. Half-metallic materials are considered one of the "holy grails" of spin electronics research, and continue to be elusive. This research will help maintain and increase the momentum of the young field of spin electronics by realizing the potential of this extremely interesting class of materials that have thus far not been fully exploited. The project requires a multidisciplinary effort that will make significant contributions to scientific knowledge, education, outreach and infrastructure. Project personnel will play a key role in several ongoing education and outreach activities related to the proposed research. These include collaboration with local schools to facilitate participation by high school students in research, public tours and demonstrations.