2015 Beckman Symposium   

David Flannigan

Presentation Date:

David Flannigan

Unraveling Charge/Orbital Ordering, Magnesium and Lattice Dynamics with Ultrafast Electron Microscopy

Univeristy of Minnesota

Chemical Engineering & Materials Science

Development of ultrafast experimental methods that can directly probe atomic positions is a rapidly growing and evolving area that has already produced major technological advances as well as increased understanding of fundamental structure-function relationships in a wide variety of chemical and materials systems. Among these methods, ultrafast electron microscopy (UEM) is especially powerful, as it enables femtosecond studies to be conducted in real (imaging), momentum (diffraction), and energy (spectroscopy) space. Currently, one of the most exciting yet challenging areas of research is in achieving angstrom-scale, real-space imaging with femtosecond temporal resolution. The challenges are several-fold and will require a delicate balance of instrumentation development and extension of accessible experimental parameter space. To this end, our research is comprised of two main components that we are pursuing simultaneously: (1) development of new UEM instrumentation, methods, and techniques, and (2) application of these newly-developed approaches to ultrafast studies of structural and charge-orbital-spin ordering dynamics in layered strongly-correlated compounds. The goal of component (1) is to drive UEM real-space resolution into the sub-nanometer regime such that inhomogeneous electronic domain dynamics can be visualized while preserving coherence such that temporal and momentum-space resolutions are maintained, while that of component (2) is to unravel the electronic and lattice degrees of freedom of strongly electron-correlated compounds via direct visualization of dynamics following coherent perturbation and subsequent propagation of the system across relevant boundaries in the phase diagram. Achieving these goals will open new avenues of experimental research into a wide range of chemical, biological, and materials systems.

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