Materials with strong electronic correlations are amongst the most interesting topics at the forefront research in physics. The reason for this is that they exhibit a vast variety of fascinating phenomena with a high potential for applications, but they still are poorly understood by theory. One prototypical example is superconductivity, a pure quantum mechanism causing the electric resistance of a material to vanish upon cooling. In a certain class of superconductors, the so called cuprates, this transition from the metallic to the ideally conducting state can happen at temperatures of 135 K. This is quite remarkable as this temperature is above the boiling point of liquid nitrogen (78 K), resulting in this class of materials being a perfect candidate for future technological applications. On the other hand, the theoretical description of these systems is immensely challenging, so that no consistent theory could be established since their first discovery in 1987. This research group aims at the description of systems with unconventional superconductivity (like cuprates and nickelates) with cutting-edge quantum field theoretical techniques. Complementary techniques (multi-method) are applied for obtaining various oservables (multi-messenger) at the one- and two particle level. This agenda comprises the calculation of spectral functions as well as susceptibilities in several regimes of the phase diagrams of these materials (superconductivity, pseudogap, magnetism and Fermi liquid regimes) in order to create comprehensive physical insight.
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