Research Group Solid State Spectroscopy and Magnetochemistry in Material Science.

Molecular Magnetism.

Together with the research group for Molecular Magnetism (Head: Dr. Robert Saf) at the Institute of Chemical Technology of Organic Materials (ICTOS), our group forms the Project Group Molecular Magnetism at the Graz University of Technology, which is a participant of the ESF programme "Molecular Magnets". For many years, magnetic materials have fascinated mankind as representatives in the forefront of materials science with respect to both scientific development and new applications so relevant to society and technology. The use of magnetic materials is so widespread today such that they are almost indispensable in everyday life. Of great importance are aspects like, e.g., the magnetism of transition metal and rare-earth containing compounds, the interplay between magnetism and superconductivity, and the itinerant electron magnetism. The scientific outcome of these could lead to new magnetic devices for various applications. In short, molecular magnetism deals with the chemistry and physics of molecular aggregates having open-shell units, i.e., their electronic angular momenta reside primarily in p-states of the organic, molecule or polymer-based magnetic units of the lattice thus capable of generating ferro- or antiferromagnetic trends. The magnetic effect can be strengthened by designing and preparing composite materials (e.g., doping with 3d- or 4f-species of inorganic partner chemicals).

We have already got first results using specially selected surfactants and paramagnetic guest molecules with iron salts in mesoporous materials. Our aims are into the directions of the design and investigations of the physical properties of other supramolecular assemblies showing bulk magnetic properties such as long-range magnetic ordering (molecular magnets) or bistability with a hysteresis behaviour as an indication for memory effects on the system. Furthermore, we are interested in the design of relatively large, but finite, magnetic clusters that act as small magnetic particles of nanoscale size.

Three research activities in the field of molecular magnetism are pursued in our group:

• Magnetic exchange interaction in amorphous materials (doped glasses, sol-gel materials, polymer films). The aim here is to investigate the feasibility of including molecular complexes which show magnetic exchange interaction into amorphous matrices. The challenge is the preservation of the local structure of complex molecules, in particular the small metal-metal distances, when the molecules are incorporated into disordered environments. Part of these activities are covered by the research project P10713-CHE Exchange Interaction in Glasses and Zeolites (granted by the Austrian Science Foundation FWF to Dr. Karl Gatterer).
• Magnetic property changes of spinels upon dilution. Chalcogenide spinels show semiconducting and magnetic properties, which can be tuned by cation subsitution. It is therefore of interest to examine their magnetic properties in detail as a fuction of dilution with non-magnetic ions to observe the disruption of long range order and its replacement by finite clusters at the percolation limit.
• Synthesis and characterisation of mesoporous surfactant-metal(hydr)oxide composites with inorganic parts containing transition metal (Fe, Mn, Cr) (hydr)oxides. The aim is the creation of new ferro- or ferrimagnetic mesoporous phases and the investigation of their magnetism as a function of different preparative methods in order to obtain a deeper understanding of the properties of these hybrid materials. Part of these activities are covered by the research project 7110 Mesostructured metal(hydr)oxide-surfactant Composites; Novel routes to nanostructured magnetic materials (granted by the Austrian National Bank to Dr. Karl Gatterer).

International Cooperations:

• Prof. Peter Day [Director of the Royal Institution of Great Britain, London (UK)];
• Dr. Simon Carling [The Royal Institution of Great Britain, London (UK)];
• Prof. Galen D. Stucky [Department of Chemistry and Materials Department, University of California at Santa Barbara, CA (USA)];
• Dr. Vojdzlaw Srdanow [Department of Chemistry, Institute of Polymers and Organic Solids, University of California at Santa Barbara, CA (USA)].

Publications:

• project P10713.

Current fields of research.
Research Group Solid State Spectroscopy and Magnetochemistry in Material Science.