The old paradigm of the representation analysis RA approach which uses only the magnetic representation decomposed into irreducible representations is still active in the neutron diffraction community. However, in many cases the use of RA together with Shubnikov group symmetry or with magnetic superspace 3D+n groups allows us to find a hidden symmetry, which is not evident from the RA alone. The most demonstrative examples are topological spin structures, multiferroics and charge ordering systems. Identifying the new symmetry that appears below a phase transition often allows one to identify the key properties of the new phase.
We search for frustrated magnets with non-trivial topological properties, aiming to unveil and exploit new unconventional states and to work out the clarifying models. One celebrated example is an AFM spinel MnSc2S4 studied by neutron scattering.
This project is an attempt to change a material's composition reversibly in order to explore magnetic phase transitions driven by spatial ordering of mixed oxidation state cations. The compositional changes are invoked by electrochemical lithiation.
This project is dedicated to the study of complex ordering phenomena and associated changes in the physical and chemical properties in non-stoichiometric solid oxides by controlling the oxygen content. These compounds are complex due to the many active degrees of freedom such as charge, spin and orbital ordering, which interact in a competitive, synergetic way, and are of great interest for applications in oxygen sensors, oxygen membranes or as electrolytes in solid-oxide fuel cells.
High pressure and high temperature conditions allow for syntheses of new compounds with compositions that were not accessible in the past. We use neutron and synchrotron diffraction techniques to precisely study their crystal and magnetic structures and correlate these to the peculiar physical properties of the novel materials.
Neutron reflectometry is used to deduce the lithium concentration and distribution in battery electrodes during operation. The main focus up to now is on the formation of Si-Li phases and the related swelling of the electrode.
This project address the interesting structure-property relationships of Cr(II) and Cu(II) fluoroperovskites that emerge from their distorted crystal structure induced by the Jahn-Teller active states d4 and d9. The electron configuration corresponds to that of the manganese and copper oxides, which show a multitude of exciting physical properties such as magnetoresistance and superconductivity.