So-called "Single Molecule Magnets" (SMM), i.e. molecular entities that are capable of magnetically storing a bit of information at cryogenic temperatures, are in the focus of very intense research by both physicists and chemists. We are involved both in the synthesis of new systems and in the physical characterisation by magnetic measurements and inelastic neutron scattering (INS). The latter technique proves to be highly valuable to gain detailed insight into the mechanisms behind the SMM phenomenon. In particular, we use it to determine energy splittings in the electronic ground state resulting from exchange and anisotropy interactions. These can in turn be used to rationalise the magnetisation tunneling processes and their kinetics. This research is characterised by numerous international collaborations.
Our work on quantum phase transitions in dimer-based copper halides focussed on the direct tuning of quantum fluctuations in TlCuCl3 by pressure application and on the investigation, including spin dynamics and phase diagram, of the new organic spin ladder material (C5H12N)2CuBr4. We succeeded to grow for the first time fully deuterated and gram-sized high quality single crystals of the latter compound. Neutron scattering experiments were performed at SINQ (PSI) and ILL Grenoble (F), and extensive bulk measurements (specific heat, magnetisation, magneto-caloric effect, thermal expansion) at HMI Berlin (D), NHMFL Los Alamos (US), and University of Cologne (D).