Ultrafast control of the electronic properties of TiSe₂ with light

TiSe₂ is a prototypical charge density wave (CDW) material, featuring a complex interplay of many-body interactions such as electron-electron, electron-lattice and electron-hole. Despite being studied for decades, it is still not clear what role these different degrees of freedoms play in stabilizing the CDW phase and how they are related to the pressure and doping induced superconductivity in this material. The ideal tool to study such a strongly correlated material is time and angular resolved photoelectron spectroscopy (trARPES), as it allows to not only map the response of the CDW order parameter to optical excitation, but also to directly visualize changes in many body interactions in the form of band renormalizations. In this work, we will show how the electronic structure of TiSe₂ can be precisely controlled by optical excitation as a function of time and fluence. Our results are then interpreted with the aid of DFT calculations.