Fermi surface is at the heart of our understanding of the properties of metals and strongly correlated systems. Abrupt change in the Fermi surface topology, also called Lifshitz ransitions, can lead to the emergence of fascinating phenomena like colossal magnetoresistance and superconductivity. While Lifshitz transitions have been demonstrated for a broad range of materials and using different types of external perturbations like strain, doping, pressure and temperature, a protocol for ultrafast and transient switching of the Fermi surface topology has not been demonstrated yet. In this talk, I will show that using time-resolved ultidimensional spectroscopy, we have recently demonstrated a scheme based on ultrafast light-induced photodoping that drives a Lifshitz transition in the topological type-II Weyl semimetal Td-MoTe2.
I will also present some technical aspects of our time-resolved multidimensional photoelectron spectroscopy setup based on an ultrafast 500 kHz HHG-based XUV light source and on a time-of-flight momentum microscope detector.