Materials containing transition metal or rare-earth elements create fascinating properties such as unconventional superconductivity, heavy fermion behavior, nematicity, Hund’s metal physics and quantum criticality. One can even tune these materials from one exotic phase to another by tiny changes for example in pressure, magnetic field or material composition. These phenomena challenge our current understanding of condensed matter physics. They originate from interactions between electrons. The idea of describing 10²³ interacting electrons contained in a typical piece of metal seems mind-blowing. In fact, exact solution for these materials and their properties are out of reach. Instead, we try find models that capture the essential physics. The materials we are interested in are often called Quantum Materials. Their properties are shaped in an exotic way by the quantum mechanical effects of entanglement and topology acting on the many-body sytem.

 
We are interested in understanding how the electrons interact with each other to create these fascinating quantum phenomena. To this end, we employ angle-resolved photoemission spectroscopy (ARPES) to measure the electronic structure of quantum materials. We combine ARPES with in-situ tuning parameters such as unixial strain to manipulate and control the material properties. Systematic studies of the electronic structure as function of temperature and non-thermal tuning parameters allows us to connect microscopic electronic properties to the complex phase diagrams of quantum materials.