Our research group is focused on the ultrafast properties of materials, with the goal of visualizing, capturing, and directing the atomic-scale processes that underlie how materials and devices function. These processes involve time-scales extending down to 10-15 seconds, and represent fundamental limits to device efficiency, speed, and reliability. Broad applications to information storage technologies, energy-related materials, and nanoscale optoelectronic devices follow from this work. By seeing directly how these processes occur in real time and in-situ, we seek to go one step further and engineer new functionality by directly manipulating atomic and electronic degrees of freedom and harnessing the flow energy between them. These experiments are interdisciplinary and span a range of fields within materials science, merging aspects of fundamental and applied science in ways that have never been possible before.

We are working on elucidating how nanoscale materials transform and the associated time-scales in a variety of semiconducting, superionic, topological, phase-change, and ferroic nanomaterials with applications to next generation electrochemical and information storage technologies. These measurements make use of x-ray scattering, spectroscopy, ultrafast electron diffraction, and nonlinear optical techniques to visualize the first steps in these processes. New and ongoing projects include the investigation of topological switching processes in atomically-thin materials, resolving the structural deformations following absorption of a photon in the hybrid perovskites, and investigation of the dynamics of ion hopping in electrochemical systems via in-situ dynamical probes.

We are also interested in the use of light to manipulate and engineer the functionality of materials. Experiments make use of light ranging from x-rays to far infrared terahertz (THz) frequency light pulses, approaching the limit where the electric and magnetic field turn on and then turn off within a single optical cycle, as a means of controlling the atomic-scale pathways materials follow. Current work is focused on investigating mechanisms for all-optical switching in ferroelectric and multiferroic materials, and their ultrafast photovoltaic response using both optical and x-ray probes. We are looking at THz-driven processes in phase-change materials, and the first steps in field-driven processes in resistive switching devices. And we are investigating how one can use these approaches to manipulate ion intercalation dynamics in quasi-two-dimensional materials as a probe of the associated transition state. These same light pulses are also used as a femtosecond resolution spectroscopic probe of carrier dynamics in a range of materials for energy conversion applications. Finally a new effort is focused on the dynamical processes occurring in next generation photovoltaic materials and light emitters such as the hybrid perovskites, probing the atomic-scale mechanisms that underlie the unique optoelectronic functionality of these materials.