Date: Tuesday, May 4, 2021
Time: 11:00 am
Talk Title: Understanding photoexcited state dynamics at the nanoscale in strongly-correlated systems through ab-initio simulations
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Abstract:
The interplay between charge, spin, and lattice degrees of freedom in strongly correlated systems under external stimuli gives rise to several fascinating phenomena. In these materials, the high-resolution ultrafast pump-probe spectroscopy experiments have revealed interesting physical effects, such as photoinduced phase transitions, photovoltaic effects, and transient “hidden” phases. However, the intrinsic mechanisms that govern the photoinduced processes, and are important from the application point of view, are not yet fully understood. At the heart of them lies the microscopic understanding of the energy conversion processes. Theoretically, the study of such processes is a challenging task which requires methods that can cover timescales of various active degrees of freedom. In this talk, I will discuss the microscopic modeling of relaxation dynamics and will present simulation results for perovskite manganites and nickelates showing the role of spin and phonons in the photoinduced dynamics. In the charge-ordered stripe phase, the photoinduced phase transitions can be highly selective depending on the light-pulse intensity and its polarization. In the second part of my talk, I will show the simulation results of photocurrent generation and its evolution and will discuss ways to enhance the photovoltaic response in ferroelectric systems with strong interactions. I will give an insight into the possible spin- and lattice-assisted relaxation mechanisms.
