Seminarium "Modeling of Complex Systems"

Scientists are uncovering fascinating ways in which light interacts with electrons and vibrations in ultra-thin layers of special materials called transition metal dichalcogenides. When exposed to light, electrons in these materials get "excited" and begin to transfer energy to the atoms around them. This process, involving vibrations known as phonons, is key to controlling how these materials conduct heat and electricity, which could make them valuable for next-gen electronics. Combining femtosecond electron diffraction experiments with our theoretical calculations, we studied in WSe2 how excited electrons distribute their energy across different phonons. We found that this energy transfer is not uniform; it varies with momentum and initially creates an uneven, “non-thermal” phonon distribution. Over time, however, this distribution evens out, leading to a stable, thermal state.Going further, we studied more recently the interaction between WSe2 and MoSe2 when stacked together in a layered structure. Here, we observed a strong interlayer connection: phonons in one layer influence excitations (excitons) in the other. Using Raman scattering techniques together with density-functional calculations, we show that MoSe2 vibrations couple stronger to WSe2 excitons than vice versa, highlighting a unique coupling effect that cannot be understood by looking at either layer alone.Instead, it is the interaction between layers that creates new electronic and vibrational behaviors. These findings might help to develop finely-tuned, light-responsive materials with applications in optoelectronics and quantum technologies.

The seminar is held in hybrid mode:Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/97084466352?pwd=REoPAygK6p2JyEJevuxObOry69lc6r.1Meeting ID: 970 8446 6352Passcode: 982002