Research

 

Novel States of Matter on the Border of Magnetism

The research of our team focuses on the discovery and understanding of new phenomena and novel quantum states in strongly correlated electron materials by means of experiments performed at very low temperatures and high magnetic fields. This includes quantum phase transitions, non-Fermi-liquid phenomena and unconventional superconductivity in metals - mostly 3d-electron and 4f -electron systems - in particular in heavy- fermion compounds.
The beauty of these materials can essentially be found in their complex magnetic and band structures. The basic strategy behind our research is to modify these structures by external actions, e.g. by applying an external magnetic field, in order to tune the selected material between competing ground states, i.e. across quantum phase transitions. Famous examples are antiferromagnetic or ferromagnetic quantum phase transitions, metamagnetic or Lifshitz transitions. Here, unusual forms of magnetism, unconventional superconductivity or even more subtle ordered states may appear. Importantly, some of the materials discovered by our team are used for practical applications like the adiabatic demagnetization technique for refrigeration.
This research requires a large variety of experimental techniques that have to be applied with high precision. Our specific expertise lies in thermodynamic, magnetic, thermal and electrical transport experiments, all with the highest modern standards of performance. For instance, we have developed a set-up for thermal expansion that can detect a change in length of about 10-12 meter and a Faraday magnetometer that can measure the magnetization of small samples down to 0.05 K and up to 12 T with a resolution close to that of a SQUID.  Our overall suite of equipment means that we are ideally placed to take on the challenges of a fast-moving field. 
 
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