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.
