Photon-Induced Magnetization Changes in Single-Molecule Magnets

Abstract

Microwave radiation applied to single-molecule magnets can induce large magnetization changes when the radiation is resonant with transitions between spin levels. These changes are interpreted as due to resonant heating of the sample by the microwaves. Pulsed-radiation studies show that the magnetization continues to decrease after the radiation has been turned off with a rate that is consistent with the spin's characteristic relaxation rate. The measured rate increases with pulse duration and microwave power, indicating that greater absorbed radiation energy results in a higher sample temperature. We also performed numerical simulations that qualitatively reproduce many of the experimental results. Our results indicate that experiments aimed at measuring the magnetization dynamics between two levels resonant with the radiation must be done much faster than the >20-microsecond time scales probed in these experiments.