LASER-ARPES · Laser based photoemission: revolutionizing the spectroscopy of correlated electrons

It is proposed to develop a novel instrument for angular resolved photoelectron spectroscopy (ARPES) by combining a laser based ultraviolet light source with a state-of-the-art electron spectrometer. This combination will be unique in Europe and will push this important technique to an entirely new level of resolution, comparable to the thermal broadening at 1 K and nearly an order of magnitude lower than the resolution achievable in practical ARPES experiments with the latest synchrotron light sources. The low photon energy of this new source will also markedly enhance the bulk sensitivity of ARPES and thus enable the investigation of interesting materials that were not accessible so far. These new capabilities will be used to study the subtle quantum many-body states of correlated electrons in transition metal oxides, a frontier topic in condensed-matter physics. Specifically, we will focus on electronic instabilities in perovskites and elucidate how different degrees of freedom play together to determine the often vastly different properties of chemically closely related materials. Moreover, we will apply modern electron spectroscopy to correlated molecular solids with complex phase diagrams that challenge existing theory for satisfactory explanations. This field is largely unexplored but is fundamental for advances in molecular electronics.