Event
Special Physical Chemistry Seminar: Frank Gao (The University of Texas at Austin)
Elucidating Material Functionalities Out-Of-Equilibrium: Nonlinear and Intertwined Dynamics in Complex Systems
Elucidating Material Functionalities Out-Of-Equilibrium: Nonlinear and Intertwined Dynamics in Complex Systems
Abstract: Material functionalities, whether arising from chemical reactions, phase transitions, or physicochemical transformations, are fundamentally governed by nonequilibrium dynamics. In complex materials, the interplay among diverse degrees of freedom—such as charge, lattice, and spin—gives rise to a wide variety of emergent behaviors. Unlocking these intricate interactions is crucial for achieving control over material properties and enabling advanced functionalities.
In this talk, I will highlight recent progress in uncovering and manipulating these dynamic interactions within complex systems. First, I will discuss the discovery of nonlinear couplings between distinct spin waves in noncollinear magnets, revealed through multidimensional terahertz spectroscopy. I will demonstrate that these previously elusive interactions are powerful tools that can be harnessed to shape material ground states and process spin-encoded information at terahertz speeds.
Next, I will turn to the layered multiferroic NiI₂, whose electron spins spontaneously organize into chiral helices that intricately couple the material's electric and magnetic properties. By employing complementary ultrafast microscopy probes, we disentangle the intertwined polarization and magnetization dynamics, revealing a record-breaking dynamic magnetoelectric coupling and natural optical activity at terahertz frequencies. This work unveils the critical factors necessary for enhanced coupling strengths and paves the way for high-performance, atomically thin magnetoelectric devices.
Bio: Dr. Frank Gao earned his B.S. in Chemical Physics from the University of Toronto in 2015 and his Ph.D. in Physical Chemistry from MIT in 2021 under the supervision of Prof. Keith A. Nelson, supported by an NSERC postgraduate fellowship. During his Ph.D., he investigated the ultrafast dynamics of irreversible processes, including photochemical reactions and photoinduced phase transitions, utilizing time-resolved optical, mid-infrared, and terahertz spectroscopies. He is currently a TQI Postdoctoral Fellow at the University of Texas at Austin, working with Prof. Edoardo Baldini to study emergent quantum materials through nonlinear terahertz spectroscopy and ultrafast optical microscopy techniques.