Group Leader Profiles

The emergence of strongly correlated electronic phases remains one of the unsolved puzzles of modern condensed matter physics. In low dimensions, the strength of interactions between electrons is enhanced, which make these systems prime candidate to understand the origin of emerging electronic phases, with the added benefit of metrology and quantum computing applications. Our research group combines nanofabrication of graphene structures, local probes and quantum transport at ultra-low temperatures to induce, control and explore strong electron interactions in one- and two-dimensional systems. We experimentally control the magnitude of electron-electron interactions in quantum materials to understand the interplay between quantum confinement, non-trivial topology and interaction strength.

The research in our group focuses on the study of transition-metal oxide thin films and multilayers using resonant x-ray spectroscopy. Our goal is to combine different quantum materials in a heterostructure to stabilize new phases with functional properties that can be used, for example, in sensor, memory or logic applications.

Our research seeks to elucidate the links between the structure and properties of technologically-relevant materials. The primary goal of our work is to advance electrochemical energy storage through the design and control of the atomic and electronic structure, and microstructure of materials, including the discovery of novel compounds, and through the optimization of interfaces and composite structures in devices. Our approach encompasses innovative synthesis approaches, electrochemical testing, as well as the in-depth investigation of structural and electronic phenomena taking place in the electrodes, in the electrolyte, and at their interfaces during battery function. For this, we use complementary diagnostic tools, from state-of-the-art spectroscopy, to diffraction/scattering, to electron microscopy. In particular, we develop high resolution solid-state nuclear magnetic resonance (NMR) spectroscopy, operando and in situ NMR and electron paramagnetic resonance (EPR) spectroscopy, magnetometry, and magnetic resonance imaging (MRI). Another pillar of our work is the development of first principles and statistical mechanics computations to facilitate the interpretation of our experimental results.

Our research group is at the forefront of creating functional materials through the chemistry of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) for catalytic applications. We specialize in the development of MOCOF, the fusion of MOF and COF chemistry, to realize materials with superior properties, as well as creating well-defined catalytic sites in MOFs/COFs/MOCOFs.

Our expertise spans coordination chemistry, organic chemistry, and materials science, supported by an extensive range of analytical techniques. These skills empower us to thoroughly understand and design the synthetic processes, structures, and catalytic behaviors of porous crystalline materials. By leveraging our knowledge and methodologies, we strive to push the boundaries of materials science and chemistry.

Our interdisciplinary research group explores how to teach crystals tricks of living matter by investigating dynamic features of molecular framework materials such as metal-organic and covalent organic frameworks (MOFs and COFs). By specifically tuning the structural topology of the framework, we create soft porous crystals which exhibit pore contraction and/or expansion as a response to the adsorption of gases and fluids or external triggers such as light irradiation. Such materials can act as responsive cargo-release systems, nanoscopic sensors or feature counterintuitive phenomena such as negative gas adsorption. We furthermore construct frameworks which contain molecular machines such as light-driven molecular motors and switches as responsive and intrinsically dynamic building blocks. We aim towards collective operating molecular machines in the solid state which are able to actively transport molecules in the pore space and facilitate dynamic conversion and storage of energy carriers and other small molecules. Our diverse team uses a wide range of synthetic and experimental tools and collaborates in national and international research projects to push the boundaries of dynamic features in crystalline solids.

My research interests deal with the design, synthesis and characterization of novel liquid crystalline materials, hybrid materials of dyes and liquid crystals, as well as biomaterials. We try to understand structure property relationships in such materials towards novel organic electronics, ion conductors and battery materials.

The research in my group is mainly focused on non-equilibrium phenomena in Quantum Materials as well as on novel Josephson and Proximity effects using triplet superconductors. One major direction of our actual investigations are Higgs oscillations in superconductors under non-equilibrium conditions. Employing various non-equilibrium techniques we have predicted unique effects that provide novel insights into unconventional superconductors. We collaborate with many experimental groups in Stuttgart as well as in Toyko and Vancouver within the framwork on the Max Planck--UBC--UTokyo Center for Quantum Materials. With the prediction of novel and Josephson and Proximity effects in triplet junctions my group has opened a new field of research in condensed matter physics. Finally, I pioneered a new field 'Higgs spectroscopy' where collective modes of the superconducting order parameter classifies the ground state. A new field in the area of superconductivity. Experiments have confirmed our recent predictions.

The work focuses on synthesis and detailed characterization of metal-rich compounds, preferentially containing nitrogen as a constituent. First emphasis is the design and development of preparative techniques as basis for synthesis of novel materials. Special attention is granted to structural characterization, electronic and magnetic properties as well as mechanical and chemical behavior. These data are inevitable for any detailed consideration of chemical bonding and potential applications. • Advanced solid state synthesis of functional materials including various high pressure techniques, solvothermal synthesis and crystal growth, high temperature synthesis • Solid state reaction pathways and crystal growth mechanisms • Magnetic and superconducting materials, ionic conductors

Our research group studies electronic and magnetic structures of quantum materials. A special focus is on topological materials, which exhibit unusual properties, such as exotic surface states and anomalous transport phenomena, that are unaffected by continuous deformations, e.g., stretching, compressing, or twisting. Our aim is to develop a theoretical framework to describe these topological properties, and to find new ways how to use them in the laboratory and for device applications. We seek to classify topological materials in terms of symmetries and to discover new remarkable examples. Current research priorities focus on the topological properties of nodal-line semimetals, topological metals with nodal planes,  altermagnets, and unconventional superconductors, which we study using both analytical and numerical techniques.