Fast and ultrafast dynamical processes in magnetic systems have become the subject of intense research for last the two decades, since the pioneering discovery of Beaurepaire et al. of femtosecond demagnetization in nickel by an intense laser pulse. Here, we study the magnetization dynamics from a Dirac-Kohn-Sham framework, by deriving the extended Pauli Hamiltonian which includes the nonrelativistic Pauli Hamiltonian and additional relativistic terms.
