The first known quantitative measurements of an ultrafast relaxation process in yttrium iron garnet (YIG) are presented. Decay out of the initially excited crystal field state at 16 000 cm−1 was observed to occur in 100 ± 40 fsec. Additional measurements performed on YGG:Fe (Y3Ga4.8Fe0.2O12) at 298 and 2.6 K implicate the involvement of charge-transfer states in this ultrafast relaxation. Lifetimes of less than 2 fsec are indicated for pure charge-transfer states. No dynamic manifestation of the strong antiferromagnetic exchange coupling between iron ions in YIG is evident.
© 1985 Optical Society of America
B. I. Greene and R. Wolfe, "Femtosecond relaxation dynamics in magnetic garnets," J. Opt. Soc. Am. B 2, 600-605 (1985)