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New methods to induce magnetization switching in a thin ferromagnetic material using femtosecond laser pulses without the assistance of an applied external magnetic field have recently attracted a lot of interest. It has been shown that by optically triggering the reversal of the magnetization in a GdFeCo layer, the magnetization of a nearby ferromagnetic thin film can also be reversed via spin currents originating in the GdFeCo layer. Here, using a similar structure, it is shown that the magnetization reversal of the GdFeCo is not required in order to reverse the magnetization of the ferromagnetic thin film. This switching is attributed to the ultrafast spin current and can be generated by the GdFeCo demagnetization. A larger energy efficiency of the ferromagnetic layer single pulse switching is obtained for a GdFeCo with a larger Gd concentration. Those ultrafast and energy efficient switchings observed in such spintronic devices open a new path toward ultrafast and energy efficient magnetic memories. [ABSTRACT FROM AUTHOR]

We review the phenomenology of light-induced ultrafast magnetization dynamics, with emphasis on metallic compounds. The interaction of femtosecond laser pulses with magnetic thin films induces a wide range of out of equilibrium phenomena, leading to an ultrafast demagnetization, and a subsequent magnetization dynamics. The latter can lead to a deterministic reversal of the magnetization or allow for the controlled motion of domain walls. Those light-induced magnetization manipulations have potential application for ultrafast and energy efficient spintronic. The review summarizes experimental results and theoretical approaches on demagnetization and the all-optical helicity-dependent switching of the magnetization, whose underlying mechanism(s) are still heavily debated, even after 25 years of intensive research. • The magnetic excitations responsible for the ultrafast demagnetization are debated. • A broad overview of the mechanisms through which they could be generated is provided. • Criteria allowing for the helicity-dependent all-optical switching are reviewed. • The origin of the helicity-dependence is examined. [ABSTRACT FROM AUTHOR]