The junior research group is set up to strengthen the collaboration between the HZB and IFW in the field of photoemission spectroscopy of quantum materials by means of further improvement of experimental equipment at BESSY synchrotron. Nowadays the successful photoemission experiments require state-of-the-art combination of synchrotron beamline and end-station with the spectrometer. It should provide the high momentum and energy resolution, broad temperature range at which measurements are possible with the emphasis of the coldest side, as well as a high degree of the automatization. A special importance have the integration of all the components including the monochromator of the beamline, cryostat, electron energy analyzer and manipulator into a common system with flexible communication between all these components and comfortable user interface. With the help of such improved experimental equipment the group is supposed to demonstrate how the modern photoemission experiment can contribute to design and understanding of novel quantum functional materials.
Our research deals with materials-oriented experimental condensed matter research with particular emphasis on quantum materials and nanoscale systems. Besides fundamental physics and materials syntheses we are also involved in application oriented research which ranges from electronics to biomedical applications.
In Quantum Materials a possible potential for technological applications emerges from their complex, quantum mechanical electronic properties. The complex electronic properties of " Quantum Materials" may result from the interplay and unusual ordering phenomena of electronic spin , orbital and charge degrees of freedom and can be observed in the context of topologically protected spin or charge states
The above mentioned physical material's properties manifest in a number of material classes: in certain families of transition-metal oxides, in molecular solids and in a range of intermetallic materials. What sets these systems apart is that their valence and conduction electrons typically retain to some extent their atomic character, resulting in a rich interplay of localized and delocalized electronic degrees of freedom. This renders these materials both practically and conceptually very different from simple metals and semiconductors with well-understood itinerant quasi-particles. Often the quantum mechanical interplay between the localized and delocalized electronic degrees of freedom leads to anomalous charge transport properties, for instance due to the presence of metal-insulator transitions, and exceptional types of ordering phenomena, such as unconventional forms of superconductivity and quantum magnetism. Functionalities that arise from this are for instance large magnetocaloric effects, high temperature superconductivity, magnetism with very strong anisotropy and colossal/giant magnetoresistance.
The plethora of spectacular and surprising phenomena that can occur in Quantum Materials poses one of the greatest set of challenges for cutting-edge experimental and theoretical condensed matter physics. As a rule material-specific predictions for the occurrence of many of these phenomena are very difficult, even if some of the presently booming research topics in this field, for instance the investigation of magnetic skyrmions and new topological states of matter, have emerged from a strong theoretical research effort and remain being strongly pushed by it.
“Nanometer-scale Quantum Materials”
When the dimensions of materials are restricted to the nanometer length-scale, new electronic properties emerge. This is related to the fact that any macroscopic object, when scaled down to a nanometer-scale, starts exhibiting distinct quantum mechanical properties. However, at the nanoscale also entirely new physical properties may emerge, for instance at surfaces and interfaces of topological insulators (TIs) where the spin of surface electrons is locked to their momentum, a property that is interesting in the context of spintronics.
The technological ability to engineer and shape materials at the nanoscale opens up a very well-defined road to control the materials properties and functionality in a systematic manner. It requires the synthesis, modelling and structuring of nanosystems, which is pursued in the context of a broad span of nanoparticles, ranging from endohedral fullerenes, carbon-based buckytubes to intermetallic or oxide nanoparticles. This combined approach is also the basis for the design of interfaces and heterostructures of superconducting materials, magnetic systems and molecular solids. In these heterostructures charge transfer effects at or across interfaces are decisive for the properties and functionality. An advantage of such interfaces is that they can be modified and engineered to a much greater extent than bulk Quantum Materials.
Building on the traditional strength in the field of Quantum Materials, and in order to strengthen in particular this research area and its potential for device applications, in 2013 the Center for Transport and Devices of Emergent Materials (CTD) has been founded together with the TU Dresden.
Unique methodology: search, synthesis, analysis, and application potential of new materials
Our research teams search for new materials with the outlined unusual electronic properties and study their fundamental physical properties using a broad range of experimental techniques. Customized high resolution methodology is developed according to the specific scientific questions and phenomena, and finally, based on the experimental results, the chemistry, the morphology and the intrinsic physical properties of the materials are optimized with respect to technical applications. Some of the methodological developments of our institute push the limits of current condensed matter research. Such set-ups as well as the special infrastructure for materials synthesis are made available to cooperation partners at universities (crystal growth laboratory), worldwide users (ARPES measurement stations at the Berlin Synchrotron BESSY), or to industry partners (laboratory for spectroelectrochemistry).
Application-driven research activities
Based on our scientific expertise, our methodological experience, and based on our dedicated knowledge of specific materials classes, we also perform application-driven research in close cooperation with various industry partners. In many of these activities key challenges of the modern industrial and information society are addressed. For example, there are projects in cancer research based on our knowledge of molecular nanostructures.
Additionally, our specific methodology and expertise for spectroelectrochemistry, magnetic materials, and oxide nanomaterials is used in industry projects concerning energy and/or mobility. The activities on novel magnetic materials are also motivated by the urgent issues of resources and sustainability. Moreover, the industry-oriented research of our institute includes since many years the topic "Surface Acoustic Waves (SAW)" dealing with innovative micro-acoustic components and devices as well as the associated high-tech materials and technologies. The IFW-driven "SAWLab Saxony - Competence Center for Acoustoelectronic Phenomena, Technologies and Devices" aims to bundle our profound SAW knowledge with experience and demands of several small and medium-sized Saxon high-tech companies fostering the close cooperation of our institute with the regional industry.