Electron spin dynamics of Ce3+ ions in YAG crystals studied by pulse-EPR and pump-probe Faraday rotation

The spin relaxation dynamics of Ce3+ ions in heavily cerium-doped YAG crystals is studied using pulse-electron paramagnetic resonance and time-resolved pump-probe Faraday rotation. Both techniques address the 4f ground state, while pump-probe Faraday rotation also provides access to the excited 5d state. We measure a millisecond spin-lattice relaxation time T1, a microsecond spin coherence time T2, and a ∼10 ns inhomogeneous spin dephasing time T2* for the Ce3+ ground state at low temperatures. The spin-lattice relaxation of Ce3+ ions is due to modified Raman processes involving the optical phonon mode at ∼125cm−1. The relaxation at higher temperature goes through a first excited level of the F522 term at about ℏω≈228cm−1. Effects provided by the hyperfine interaction of the Ce3+ with the Al27 nuclei are observed.