Magnetic probes to study photoactivated processes in mixed ionic-electronic conductors

The magnetic state of atoms and ions is directly linked to their electronic properties and hence provides a sensitive probe to study novel materials. We employ dc/ac magnetisation as well as X-band and high-frequency electron paramagnetic resonance (EPR) studies to investigate light- and electrochemically induced ionic and electronic effects. While the static magnetic properties provide information on the ground state and are particularly powerful to identify changes between magnetic and non-magnetic oxidation states, EPR is extremely sensitive to discriminate magnetic valence states, to determine the nature and crystalline environment of defects and can provide information on the associated dynamics. We use these features to study photo-generated microsecond long-living states in magnetic oxides. Specifically, X-band EPR (dark and illuminated), light-induced SQUID studies, and high-frequency EPR studies will be performed. On the intermediate time-scale of the project, we will study hybrid organic-inorganic metal-halide perovskites (HOIPs) to provide complimentary information to the Deschler group on the interplay of electronic and ionic transport in these materials. HOIPs are also investigated with AGs Ludwig, Blasco, and Deschler regarding charge-ion conversion and energy storage mechanisms as they combine promising transport properties in the inorganic parts with functionality of the organic molecular components; both components as well as the space between the perovskite layers will be tailored for efficient charge storage.