Highly efficient all-optical switching of magnetization in GdFeCo microstructures by interference-enhanced absorption of light

Employing magnetization-sensitive microscopy techniques, we address the light-induced magnetization dynamics of patterned samples of rare-earth transitionmetal alloys. We experimentally find that smaller structures require a lower energy density to undergo all-optical switching of the magnetization. With the aid of simulations we explain this reduction in terms of enhanced light absorption by interference of the light within the structure. This results in a decrease of about 60% in the energy densities required for all-optical switching compared with those in continuous thin films of the same alloy. Moreover, we envisage that an energy lower than 10 fJ should be sufficient to switch a 20 x 20 nm(2) structure.