This book comprises three different types of unconventional correlated systems. The first part of this work addresses the open shell alkali sesquioxides. In contrast to theoretical predictions, which suggested half-metallic ferromagnetism for rubidium sesquioxide, dominating antiferromagnetic interactions were found in the experiments. A symmetry reduction and strong electronic correlations of this highly molecular could explain the peculiarities of this system. The second part is about intermetallic Heusler superconductors. All of these were rationally designed using the van Hove scenario as...