Prof. Dr. Peter Wölfle
Prof. Dr. Raymond Frésard

This work aims to propose techniques to access physical properties at intermediate temperature scales. These methods include both numerical ones on the one hand and analytic ones on the other. The former ones operate within the framework of the density matrix renormalization group aiming to characterize a system at finite temperature by a set of states. The latter ones are applied to the density of states of slightly modified two-dimensional systems which are believed to describe the delafossite compounds. These materials recently attracted a huge interest due to their thermoelectric properties, but have revealed a behavior at intermediate temperatures resembling a Fermi liquid one. This behavior is examined with the proposed methods. Furthermore, it is shown that properties of the density of states as well as the charge carrier density of those materials can be extracted from a careful study.