Measurement of magnetization dynamics in single-molecule magnets induced by pulsed millimeter-wave radiation

We describe an experiment aimed at measuring the spin dynamics of the Fe8 single-molecule magnet in the presence of pulsed microwave radiation. In earlier work, heating was observed after a 0.2ms pulse of intense radiation, indicating that the spin system and the lattice were out of thermal equilibrium at millisecond time scales [Bal et al., Europhys. Lett. 71, 110 (2005)]. In the current work, an inductive pickup loop is used to probe the photon-induced magnetization dynamics between only two levels of the spin system at much shorter time scales (from nanoseconds to microseconds). The relaxation time for the magnetization, induced by a pulse of radiation, is found to be on the order of 10μs.