Physics (Internal)

Magnetic properties and ultra-fast relaxation in systems of molecular nanomagnets

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract Various coherent magneto-dynamical effects can lead to a phenomenon qualitatively similar to optical superradiation (SR). The electromagnetic radiation emitted by an assembly of nano-entities (molecular crystals with single-molecule spins as large as 10, nanometer particles of ferromagnets with macrospins of the order of 10³-10⁴, dots, grains, etc.) by way of the feedback effect establishes their coherence thus greatly reducing the duration and enhancing the intensity of the deexcitation pulse. The radiation intensity is proportional to up the squared number of the spins in the system and the relaxation time is inversely proportional to the number of spins involved in the coherent motion. For nanostructures with strong confinements, SR becomes the main mechanism of relaxation to the ground state. Study of SR from molecular nanomagnets with strong indirect coupling and magnetic anisotropy requires the formulation of a microscopic theory describing dynamics and relaxation in such systems and allowing for computer simulations of the effect.