Ultrafast nonequilibrium spin dynamics in a ferromagnetic thin film

Summary form only given. Fast processes associated with changes in the magnetic properties of ferromagnetic media are of both fundamental and applied interest. While there are extensive studies of hot electron relaxation in nonmagnetic metals using ultrafast laser techniques, direct microscopic information about the spin and magnetization dynamics is very scarce. As shown here, we obtain considerable additional insight to microscopic spin dynamics of a ferromagnetically ordered system by using an ultrafast magnetooptical technique. An initially spin-polarized photoexcited gas of electrons is set up in a ferromagnetic metal film by selective excitation with a circular SHG laser beam.