Laser induced ultrafast demagnetization: an ab-initio perspective

Time-dependent density functional theory is implemented in an all electron solid-state code for the case of fully non-collinear spins. We use this to study laser induced demagnetization in Fe, Co and Ni. It is shown that this demagnetization is a two-step process: excitation of a fraction of electrons followed by spin-flip transitions of the remaining localized electrons. These results successfully explain several experimental features such as the time-lag between the start of the pulse and demagnetization and spin-flip excitations dominating the physics. We further show that it is possible to control the moment loss by tunable laser parameters like frequency, duration and intensity.