Prof. Dr. Thomas Weitz from Georg-August-Universität Göttingen

(Quantum) transport in van-der-Waals materials and organic semiconductors

One exciting endeavor of condensed matter research is to understand how electrons in a solid interact with one another and the underlying atoms. Depending on this intricate interplay, the system can have drastically different properties, for example be either insulating or superconducting. In the case that mutual electronic interaction electrons and atoms involved, one can image that developing a general understanding of this interplay is very complex. In this sense, finding experimental systems that allow systematically control of e.g. charge carrier density and/ or their mutual interaction is highly desirable. The class of organic semiconductors and van-der-Waals materials offers such tunability.

This talk will focus on two aspects of our work. First, I will discuss the electronic properties of naturally occurring Bernal bilayer graphene (BBG). It has shown to host electric-field tunable van-Hove singularities. Indeed, correlated states and even superconductivity was found close to these regions of diverging density of states. I will show how we systematically identify and explore such phases by controlling not only the density of states, the charge carrier density but also the interaction between charge carriers. Most intriguingly we identified anomalous quantum Hall and Wigner crystal phases in BBG. Second, I will present our ongoing work on semiconducting polymers where we focus on understanding electronic charge transport at the nanoscale. To this end we pattern contacts with sub 100 nm distance on thin h-BN gates with the goal to observe intra-chain transport at cryogenic temperatures.