Semiclassical methods on magnetization dynamics.

We formulate the magnetization dynamics in slowly perburbed crystals using the semiclassical description of electrons, and systematically study electric/magnetic field-induced effects. The geometric phase effects are found important in the magnetization dynamics. In the presence of electric field, spin orbital torques is reformulated in the language of Berry curvature. As a complete first order theory, electric field influence on damping and gyromagnetic ratio is also studied as non-equilibrium electronic contribution. In the presence of magnetic field, we find correction on gyromagnetic ratio from the instrinsic electronic contribution in terms of second chern form. This correction contains a combine effect of charge pumping and spin transfer torque in inhomegeneous system, motive force and spin orbital torque and a new term due to density of states correction. Our theory unifies those seperated discussions and gives new contribution.