Excellence in Research: First Principles Defect Engineering of Plasmonic Diluted Magnetic Semiconducting Oxide Nanocrystals

卓越研究：等离子体稀释磁性半导体氧化物纳米晶体的第一原理缺陷工程

• 批准号: 2013854
• 负责人: Mogus Mochena
• 金额: $ 35万
• 依托单位: Florida Agricultural and Mechanical University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2013854&HistoricalAwards=false
• 关键词: Excellence; Research; First; Principles; Defect

Non-technical SummaryThis HBCU-UP award supports theoretical and computational research to simulate and predict novel quantum dots on the one hand and to develop a multidisciplinary computational physics program within the Department of Physics on the other. Quantum dots have been termed artificial atoms or molecules depending on their size and composition. They range in size from 1 – 100 nm in diameter and in numbers of atoms from hundreds to tens of thousands. While the composition and properties of atoms are predetermined by nature, the properties of artificial atoms or molecules can be manipulated by varying their size and composition. Myriad opportunities exist to create novel nanostructures, and this makes quantum dots a rich system for investigating fundamental physics as well as for technological applications.The project seeks to merge two different kinds of quantum dots, namely plasmonic quantum dots and diluted magnetic quantum dots. Plasmonic materials are based on collective motions of electrons in solids known as plasmons. These materials had been studied mostly on the macroscopic scale with classical electromagnetism theory until recently. A new property of plasmons known as localized surface plasmons was discovered on the surface of quantum dots a decade ago. The existing approach of classical physics has to be replaced with quantum mechanics in order to understand the emergent phenomena. But developing a new theory for a finite system such as a quantum dot requires computational methodology, since the finiteness breaks the translational symmetry often invoked to solve problems for periodic systems. The PI will apply quantum-mechanical as well as semi-classical computational techniques to study a range of plasmonic quantum dots. These dots are expected to have application in photonics and optoelectronics. On a separate track, the project will investigate the plasmonic materials for the onset of ferromagnetism when doped with a dilute amount of magnetic ions. These materials are of interest in their own right for applications to prospective quantum computers and spintronics at large. Eventually, the two tracks will be combined to see the possibility of a multifunctional novel material. The award will support the establishment of a computational physics program. The PI will work with computational physicists and computer scientists to offer courses modelled after a similar program at the Texas Advanced Computing Center (TACC). TACC resources will be used to train the students on high-performance computing platforms. During their senior year, the students will work on research problems. The course offerings and training are expected to prepare the students for jobs in high tech industry or to continue their research and computational experience into graduate school. In addition, the award will support a graduate student. The PI will be involved in outreach programs to community colleges and high schools to increase the number of students in the computational physics program.Technical SummaryThis proposal aims to design multifunctional semiconducting oxide quantum dots by co-doping them with magnetic and non-magnetic dopants. The project will have three thrusts:1) Semiconducting nanoplasmonic oxides: First-principles calculations with density functional theory and the kinetic Monte Carlo technique will be performed to develop new physical models that could address i) the effect of band-to-band transitions, ii) localization of carriers, iii) ligand and proximal effects, iv) quantum confinement effects for small-sized quantum dots, and v) fewer carriers than those of noble metal nanocrystals that are well described by the Drude-Lorentz model.2) Semiconducting oxide quantum dots doped with TMs: The evolution of ferromagnetism in semiconducting oxides is controversial in general because of the large number of competing parameters involved in the synthesis. A detailed study of the electronic and magnetic structures of transition-metal-doped semiconducting oxide quantum dots throughout a wide parameter space which covers the incorporation of varying amounts of dopant impurities, vacancies, and crystalline defects such as interstitials will be conducted.3) Plasmonic diluted magnetic semiconducting oxide quantum dots: After steps 1) and 2) have been undertaken, the combined system will be studied. The nanoplasmonic oxides will be doped with dilute amounts of transition metal atoms and the diluted magnetic oxide quantum dots with non-magnetic donors. Electronic and magnetic structures of the combined system will be compared to results from 1) and 2). The research will involve a graduate student and introduction of undergraduates to research protocols. In tandem with the research, a computational physics track will be launched that will train undergraduate students in scientific supercomputing. The computational physics program is expected to increase the number of physics majors. The PI will be also involved in outreach programs to community colleges and high schools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项HBCU-UP奖一方面支持理论和计算研究，以模拟和预测新型量子点，另一方面在物理系内开发多学科计算物理项目。量子点根据其大小和组成被称为人造原子或人造分子。它们的直径从1纳米到100纳米不等，原子数从数百到数万不等。虽然原子的组成和性质是由大自然预先决定的，但人造原子或分子的性质可以通过改变它们的大小和组成来操纵。创造新型纳米结构的机会数不胜数，这使得量子点成为研究基础物理和技术应用的丰富系统。该项目试图融合两种不同的量子点，即等离子量子点和稀释磁量子点。等离子体材料是基于被称为等离子体的固体中电子的集体运动。迄今为止，这些材料的研究大多是在宏观尺度上用经典电磁学理论进行的。十年前，人们在量子点表面发现了等离子体激元的一种新特性——局部表面等离子体激元。为了理解突现现象，现有的经典物理方法必须被量子力学所取代。但是，为有限系统（如量子点）开发新理论需要计算方法，因为有限性打破了通常用于解决周期系统问题的平移对称性。PI将应用量子力学和半经典计算技术来研究一系列等离子体量子点。这些点有望在光子学和光电子学中得到应用。在另一个单独的轨道上，该项目将研究等离子体材料在掺入稀释的磁性离子时铁磁性的开始。这些材料本身对未来的量子计算机和自旋电子学的应用很感兴趣。最终，这两种轨道将被结合起来，以看到多功能新材料的可能性。该奖项将支持建立一个计算物理项目。PI将与计算物理学家和计算机科学家合作，提供模仿德克萨斯高级计算中心（TACC）类似项目的课程。TACC资源将用于培训学生使用高性能计算平台。在他们大四的时候，学生们将研究问题。课程设置和培训旨在为学生在高科技行业的工作做好准备，或者在研究生院继续他们的研究和计算经验。此外，该奖项将支持研究生。PI将参与社区大学和高中的外展计划，以增加计算物理课程的学生人数。该方案旨在通过与磁性和非磁性掺杂剂共掺杂来设计多功能半导体氧化物量子点。该项目将有三个重点：1)半导体纳米等离子体氧化物；利用密度泛函数理论和动力学蒙特卡罗技术进行第一性原理计算，以开发新的物理模型，这些模型可以解决i)带到带跃迁的影响，ii)载流子的局部化，iii)配体和近端效应，iv)小尺寸量子点的量子约束效应，以及v)载流子比德鲁德-洛伦兹模型所描述的贵金属纳米晶体的载流子少。2)掺杂TMs的半导体氧化物量子点：由于在合成过程中涉及大量相互竞争的参数，半导体氧化物中铁磁性的演变通常是有争议的。对过渡金属掺杂半导体氧化物量子点的电子和磁性结构进行了详细的研究，该研究涵盖了不同数量的掺杂杂质、空位和晶体缺陷（如间隙）的掺入。3)等离子体稀释磁性半导体氧化物量子点：在步骤1)和步骤2)完成后，将研究组合系统。纳米等离子体氧化物将掺杂少量的过渡金属原子，而稀释后的磁性氧化物量子点将掺杂非磁性供体。结合系统的电子和磁性结构将与1)和2)的结果进行比较。这项研究将涉及一名研究生和向本科生介绍研究方案。在这项研究的同时，还将启动一个计算物理轨道，培训本科生进行科学超级计算。计算物理专业有望增加物理专业的学生数量。PI还将参与社区大学和高中的外展项目。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。