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

技术：这个职业项目将研究过渡金属氧化物纳米晶体中与光激发相干晶格运动相关的超快电子和磁化动力学以及材料性质的动态修改。到目前为止，对过渡金属氧化物的超快电子和磁学性质的研究主要集中在体表面和薄层结构上。这项研究将以化学合成的胶体纳米晶作为尺寸和组成可调的模型系统，研究纳米级过渡金属氧化物的超快电子和磁动力学。在电子自由度和自旋自由度中，相干晶格运动和材料性质的耦合性质也将被研究。为此，时间分辨瞬时吸收光谱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，将利用先进光源上的飞秒硬X射线束线以及基于激光的X射线源来研究真实空间中的结构动力学。电动力学、磁动力学和结构动力学相结合的分析将为探索纳米固体中原子在晶格中运动的时间尺度上的动态结构-性质关系提供一个独特的机会。非技术性：从这项研究中获得的知识对于理解电子和磁性与纳米尺度上的局部分子或晶格结构的耦合具有广泛的意义。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，几个纳米尺度的长度类似于聚合物分子过渡金属络合物的长度，这是另一类有趣的材料，表现出与尺寸相关的材料性质。在这方面，我们对过渡金属氧化物纳米晶体的研究可以为我们理解分子和含有部分d电子的过渡金属离子的块状固体的动态电子和磁性奠定了基础。这项研究的教育部分侧重于本科生物理和分析化学实验室课程的课程开发和高中生的推广方案。编制的课程还将作为教学资源提供给以本科生为主的机构。针对高中生的实验计划将被开发，以深入了解物理科学的真实研究，以培养对科学的兴趣，并鼓励有才华的学生将科学作为他们的职业选择。开发的计划将作为大学青年职业计划的一个新组成部分实施。该计划将由材料研究部的金属材料和纳米结构计划和化学部的实验物理化学计划共同资助。

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.