Ultrafast lattice and carrier dynamics in Weyl and Kane quantum materials

The PhD research project was focused on the ultrafast lattice and electron dynamics in quantum materials presenting Weyl- and Kane-like dispersions in the energy-momentum space. The objective was to study their peculiarities and differences on which there is a strong interest of the scientific community from the theoretical viewpoint and for their implementation in innovative electric devices. The experimental investigation was performed using laser setups generating ultrashort laser pulses, with pulse duration between tens and thousand femtoseconds depending on the phenomenon under analysis. Such instruments enable the possibility to probe the response of a material monitoring its excitation and relaxation dynamics which occur on the timescales similar and longer than the employed pulses (tens of femtoseconds to picoseconds). Moreover, various frequency ranges were utilized, going from terahertz until the hard x-rays, passing through the near infrared and visible ranges. Among the techniques, time-resolved reflectivity spectroscopies, time-resolved x-ray diffraction (using a free electron laser source) and two-dimensional terahertz spectroscopy were exploited. To rationalize the obtained results, an extended simulation activity was carried out, using open-source simulation codes based on the density functional theory to calculate electronic and optical properties from first-principles calculations together with self-developed scripts using C++ and software-specific languages.