Interplay of electron-magnon scattering and spin-orbit induced electronic spin-flip scattering in a two-band Stoner model

This paper presents a theoretical investigation of electron-magnon scattering processes in the ultrafast demagnetization in itinerant ferromagnets. In the framework of a ferromagnetic model system, we compute the spin-dependent dynamics of electrons in itinerant Bloch states by including electron-magnon and electron-electron scattering processes on an equal footing. While the former process flips the electronic spin accompanied by the creation or destruction of a magnon, the latter exchanges electronic angular momentum with the lattice due to the influence of spin-orbit coupling. We show that, for a realistic choice of the electron-magnon interaction and deposited pulse energy, the of these two different scattering mechanisms leads to the creation of magnons and a transfer of angular momentum to the lattice that constitutes an essentially nonequilibrium microscopic scenario for the ultrafast demagnetization process in itinerant ferromagnets.