Magneto-optical interactions in single-molecule magnets: Low-temperature photon-induced demagnetization

We show that the irradiation of SMM molecules at optical wavelengths can drive an increase or a decrease of the magnetic moment of a SMM, even though the energy of the photons does not correspond to a precise electronic or spin transition, the light pulse triggering a phonon-assisted spin transition. The process is sensitive to the power of the incident light. This result most probably explains why it has been so far impossible to observe the opening of the hysteresis loop on thin films of SMM with the XMCD technique. The consequences of these observations are manifold: they bring a means of controlling molecular magnets, open prospects in the field of quantum computing, and may enable the realization of coherent microwave sources through stimulated superradiance. [Display omitted]