Near- and mid-infrared excitation of ultrafast demagnetization in a cobalt multilayer system

Ultrafast demagnetization occurs when magnetic materials are excited by a sudden burst of energy, such as from an ultrashort laser pulse. After generating pulses from the ultraviolet to the mid-infrared spectral regions, the authors retrieve here the ultrafast magnetic dynamics of a multilayered cobalt ferromagnet excited by femtosecond pulses with wavelengths ranging from 0.8 to 8.7 {}m. A weak relationship between the excitation wavelength and the magnetic dynamics is uncovered as well as a significant effect of the pulse's shape and duration.