CAREER: Ultrafast Electronic, Magnetic and Coherent Lattice Dynamics and the Dynamic Structure-Property Relationship in Nanocrystalline Transition Metal Oxides

职业：纳米晶过渡金属氧化物中的超快电子、磁力和相干晶格动力学以及动态结构-性能关系

• 批准号: 0845645
• 负责人: Dong Son
• 金额: $ 40万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0845645&HistoricalAwards=false
• 关键词: CAREER; Ultrafast; Electronic; Magnetic; Coherent

TECHNICAL: This CAREER project will investigate ultrafast electronic and magnetization dynamics and the dynamic modification of material properties associated with the optically excited coherent lattice motion in transition metal oxide nanocrystals. So far, studies of the ultrafast electronic and magnetic properties of transition metal oxides are largely focused on the bulk surface and thin layer structures. The research will address the ultrafast electronic and magnetic dynamics of nanometer scale transition metal oxides using chemically synthesized colloidal nanocrystals as size and composition tunable model systems. The coupled nature of the coherent lattice motion and material properties in the electronic and spin degrees of freedom will also be investigated. For this purpose, time resolved transient absorption and Faraday rotation spectroscopy will be employed in conjunction with the time resolved x-ray absorption spectroscopy. For the latter, femtosecond hard x-ray beam line at the Advanced Light Source as well as the laser based x-ray source will be used to study the structural dynamics in real space. Combined analysis of electronic, magnetic dynamics and structural dynamics will provide a unique opportunity to explore the dynamic structure-property relationship in nanocrystalline solids on the time scale of the atomic motion in the lattice. NON-TECHNICAL: The knowledge obtained from this research has broad implications for understanding the coupling of electronic and magnetic properties with the local molecular or lattice structure in nanometer length scale. Relevant potential applications are switching and memory devices and spintronics, where the dynamic control of the electronic, magnetic and transport properties relies on the coupled nature of the electronic, spin and lattice degrees of freedom. In addition, the length scale of several nanometers is similar to that of polymeric molecular transition metal complexes, which is another interesting class of materials exhibiting size-dependent material properties. In this regard, our study in transition metal oxide nanocrystals could bridge our understanding of the dynamic electronic and magnetic properties of molecules and bulk crystalline solids both containing transition metal ions with partially filled d-electrons. The educational component of the research focuses on the curricula development for the undergraduate physical and analytical chemistry laboratory courses and the outreach program for high school students. The developed curricula will be also made available as instruction resources for predominantly undergraduate institutions. The experimental program aiming at high school students will be developed to give insight into real research in the physical sciences in order to foster interests in science and encourage the talented students to consider science as their career choice. The developed program will be implemented as a newly added component in the university run youth career program.The proposal is being jointly co-funded by the Metallic Materials and Nanostructures program in the Division of Materials Research and the Experimental Physical Chemistry program in Chemistry Division.

技术支持：这个CAREER项目将研究超快电子和磁化动力学以及与过渡金属氧化物纳米晶体中的光激发相干晶格运动相关的材料特性的动态修改。迄今为止，过渡金属氧化物超快电磁性质的研究主要集中在体相表面和薄层结构上。该研究将解决纳米尺度过渡金属氧化物的超快电子和磁性动力学，使用化学合成的胶体纳米晶体作为尺寸和成分可调的模型系统。 在电子和自旋自由度的相干晶格运动和材料特性的耦合性质也将被调查。 为此，时间分辨瞬态吸收和法拉第旋转光谱将与时间分辨X射线吸收光谱结合使用。 对于后者，飞秒硬X射线光束线在先进的光源以及激光为基础的X射线源将被用来研究结构动力学在真实的空间。电子，磁动力学和结构动力学的结合分析将提供一个独特的机会，探索在纳米晶体固体中的原子运动的时间尺度上的动态结构-性质的关系。非技术性：从这项研究中获得的知识具有广泛的意义，了解耦合的电子和磁性与当地的分子或晶格结构在纳米尺度上。 相关的潜在应用是开关和存储器件以及自旋电子学，其中电子、磁性和输运性质的动态控制依赖于电子、自旋和晶格自由度的耦合性质。 此外，几个纳米的长度尺度类似于聚合物分子过渡金属络合物的长度尺度，这是另一类有趣的材料，表现出尺寸依赖的材料性质。在这方面，我们在过渡金属氧化物纳米晶体的研究可以桥接我们的动态电子和磁性的分子和散装结晶固体都含有过渡金属离子与部分填充的d-电子的理解。教育部分的研究重点是本科物理和分析化学实验室课程的课程开发和高中学生的推广计划。编制的课程也将作为教学资源提供给主要是本科院校。 将制定针对高中生的实验方案，让学生深入了解物理科学的真实的研究，以培养对科学的兴趣，鼓励有才华的学生考虑将科学作为其职业选择。 该项目将作为大学青年就业计划的一个新的组成部分实施。该项目由材料研究部的金属材料和纳米结构项目和化学部的实验物理化学项目共同资助。