Magnetization dynamics in the single-molecule magnet Fe 8 under pulsed microwave irradiation

We present measurements on the single-molecule magnet ${\mathrm{Fe}}_{8}$ in the presence of pulsed microwave radiation at $118\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$. The spin dynamics is studied via time-resolved magnetization experiments using a Hall-probe magnetometer. We investigate the relaxation behavior of magnetization after the microwave pulse. The analysis of the experimental data is performed in terms of different contributions to the magnetization after-pulse relaxation. We find that the phonon bottleneck with a characteristic relaxation time of $\ensuremath{\sim}10\char21{}100\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ strongly affects the magnetization dynamics. In addition, the spatial effect of spin diffusion is evidenced by using samples of different sizes and different ways of the sample's irradiation with microwaves.