Abstract

The development of pump and probe optical techniques using ultrashort laser pulses has recently led to a breakthrough in the study of time-dependent magnetic phenomena. Recently,¹ we have shown that the absorption of a 60-fs duration laser pulse in a thin ferromagnetic Ni film leads to a magnetization decrease at the picosecond time scale, that can be measured using the longitudinal magneto-optical Kerr effect (MOKE). This experimental result has been explained with a phenomenological model that takes into account energy exchange between three thermodynamic reservoirs: the electrons, the spins, and the lattice. Clearly, more experimental and theoretical works are needed to achieve a microscopic description of the magnetic interactions occurring on the femtosecond time scale. It can nevertheless be expected that the spin dynamics is influenced by various parameters of the ferromagnetic material such as the exchange energy, the spinorbit coupling, or the Coulomb interaction between electrons.

© 1998 Optical Society of America