Trap state spectroscopy in CMR manganites and spinel manganates using opto-impedance

The photo-induced AC-impedance method is used as a versatile instrumentation to study the trap state densities and the carrier relaxation times in magneto-resistive manganites and magneto-conductive manganates and thus as a probe to check the crystal quality, which is important for the performance of any device material. A comparative study using compounds of different defect densities is presented. High defect concentrations in the compounds are identified through the photoresistivity and/or the photo-induced capacitive build up.