Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization

We propose a semi-classical model for femtosecond-laser induced demagnetization due to spin-polarized excited electron diffusion in the super-diffusive regime. Our approach treats the finite elapsed time and transport in space between multiple electronic collisions exactly, as well as the presence of several metal films in the sample. Solving the derived transport equation numerically we show that this mechanism accounts for the experimentally observed demagnetization within 200fs in Ni, without the need to invoke any angular momentum dissipation channel.