Ab initio theory for ultrafast magnetization dynamics with a dynamic band structure

•The contribution of electron–electron spin-flip scattering to the ultrafast demagnetization of ferromagnets after laser excitation is investigated.•Dynamical change of the band structure is taken into account on an ab initio level.•Large influence of the dynamical band structure on the magnetization dynamics is observed.•We trace electron dynamics and explain the thermalization and relaxation process after laser irradiation.•Treating the dynamical band structure yields a demagnetization comparable to the experimental one.

Laser-induced modifications of magnetic materials on very small spatial dimensions and ultrashort timescales are a promising field for novel storage and spintronic devices. Therefore, the contribution of electron–electron spin-flip scattering to the ultrafast demagnetization of ferromagnets after an ultrashort laser excitation is investigated. In this work, the dynamical change of the band structure resulting from the change of the magnetization in time is taken into account on an ab initio level. We find a large influence of the dynamical band structure on the magnetization dynamics and we illustrate the thermalization and relaxation process after laser irradiation. Treating the dynamical band structure yields a demagnetization comparable to the experimental one.