All-optical magnetization recording by tailoring optical excitation parameters

We investigate the dependency of all-optical magnetization switching on the properties of the exciting laser pulse by specifically tailoring all accessible laser parameters—pulse duration, wavelength, chirp, and bandwidth— over a wide range. Our results show that all-optical switching can be achieved with picosecond instead of femtosecond laser sources of various wavelengths, which considerably relaxes technological feasibility of this technique. The most striking implication is that, in contrast to all current knowledge, a strong photoinduced nonequilibrium in the electronic system is not necessary to achieve magnetization switching with light.