Research Projects 


Jochen Stahn (PSI) und Justin are preparing the neutron reflectometer AMOR at PSI.
Our research is directed towards developing a better understanding of the unusual electronic and magnetic properties of transition metal oxides with strongly correlated electrons. Prominent examples are the cuprate high-Tc superconductors and the recently discovered iron arsenide superconductors. We also grow and investigate various kinds of oxide-based thin films, superlattices, and heterostructures. The interfaces of these artificial materials can be grown with atomic precision. This allows us to combine materials with different order parameters and interactions and to control their proximity coupling as to achieve artificial materials with improved or novel properties and functionalities. One example is the combination of cuprate high-Tc superconductors and ferromagnetic manganites, which are well known due to their collosal magnetoresistance (CMR) effect. Here we investigate the competition between superconductivity and ferromagnetism and search for new spin- and quantum phenomena. Another example concerns the confined high mobility electron gas which develops at the interface between a LaAlO3 thin film and a SrTiO3 substrate. Last but not least some of us are also actively working on organic materials and thin films with the emphasis on their properties for application in spintronics.


Structure of Ru-1212.
Our major experimental techniques are (i) optical spectroscopy (especially ellipsometry), (ii) (low energy) muon spin rotation, (iii) and neutron reflectometry. A substantial part of these experiments is performed at large scale facilities like the Paul-Scherrer-Institut (PSI) in Villigen, Switzerland, the ANKA synchrotron source at Forschungszentrum Karlsruhe, Germany, at the FRMII reactor at the TUM Munich, Germany, the Rutherford Laboratory in Chilton, UK, or the Institute Laue Langevin (ILL) in Grenoble, France. A significant part of the optical experiments is also performed with spectrometers that are based in our laboratories in Fribourg. Furthermore, we maintain a PPMS system for electric transport and magnetization measurements, a modern AFM system and standard x-ray diffractometer. We are also operating a state-of-the-art system for the pulsed laser deposition (PLD) growth of thin films and heterostructures. Furthermore, we maintain close collaborations concerning samples growth, X-ray analysis, electron microscopy and electron spectroscopy with the groups of Philipp Aebi in the physics department, Katharina Fromm in the chemistry department, and Bernard Grobetty in the department of geosciences at Fribourg.

Our activities in Fribourg are complemented by collaborations with researchers at Paul-Scherrer-Institut (PSI) in Villigen, Schweiz; Max-Planck-Institut für Festkörperforschung (MPI-FKF) in Stuttgart, Germany; Forschungszentrum Karlsruhe in Germany; Queen Mary College in London, UK; Masaryk University in Brno, Czech Republic; Warsaw University in Poland, IIT Roorkee in India, and Industrial Research Laboratories in Lower Hutt, New Zealand.

Our research activities are embedded in the context of the Forschergruppe 538 of the Deutsche Forschungsgemeinschaft (DFG), the MaNEP program of the Swiss National Science Foundation, and the Indo-Swiss Joint Research Programme. 

 

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