The Gd–Ce Cross-Relaxation Effects in ODMR via Ce3+ Emission in Garnet Crystals

Electron paramagnetic resonance (EPR) in the ground state of Gd3+ ions in (LuGd)3 Al5O12 single crystals has been found by monitoring the Ce3+ photoluminescence intensity under circularly polarized excitation in the presence of the 35 GHz microwave field. Due to spin selection rules for optical transitions, the circularly polarized excitation allowed monitoring the populations of the Ce3+ ground-state spin sublevels, which can be changed at the EPR of Gd3+ due to Gd–Ce cross relaxation.