Low-dimensional and nanoscopic electronic systems do not only hold promise for technological applications, but also pose many fascinating theoretical issues. First and foremost, these are related to the fundamental importance of quantum mechanics in determining the properties of these systems which are situated between the microscopic world of (sub)atomic physics and the macroscopic world around us. Our research specifically addresses electronic transport in these systems, with current research addressing the following issues:
Quantum coherence and correlation effects distinguish quantum transport through nanostructures from more conventional quasiclassical transport. A flexible and intensively studied model system are quantum dots where our work has focused on strongly coupled dots, the Coulomb blockade, and the Kondo effect. Most of our current effort focuses on molecular electronics where we investigate the influence of collective modes such as molecular vibrations or spin in single-molecule transistors.
Two-dimensional electron systems
Over the past decades, two-dimensional electron systems have been the stage for a large number of discoveries, of which the quantum Hall effects are the most remarkable. As the quality of samples based on GaAs/AlGaAs heterostructures improved over time, many intricate ground states have been observed and analyzed theoretically. Our work in this area has focused on the physics of higher Landau levels, including electronic liquid-crystal states (stripe and bubble phases), negative Coulomb drag, non-Abelian quasiparticle statistics at filling factor 5/2, as well as microwave-induced zero-resistance states. Currently, our interests focus on the physics of the two-dimensional electron system in graphene (monolayers of graphite) which has recently been realized experimentally.
Exploiting the electron spin in electronics is the central aim of spintronics. Thus, understanding spin transport poses one of the major challenges in this field. Our interests in this field have focused on GaMnAs which is a promising material for spintronics applications, transport properties near ferromagnetic phase transitions, as well as the anomalous Hall effect.