RESUMEN
Ultrashort laser pulses have been used to study the effect of circularly polarized light on spins in the ferrimagnetic metal GdFeCo. By turning the sample into a multidomain state and thereby suppressing the observation of the heating effect of light, we have been able to demonstrate an ultrafast nonthermal excitation of spin waves with a phase that depends on the angular momentum of the photons. These results demonstrate the possibility of ultrafast coherent control of the magnetization in this metallic system.
RESUMEN
We experimentally demonstrate that the magnetization can be reversed in a reproducible manner by a single 40 femtosecond circularly polarized laser pulse, without any applied magnetic field. This optically induced ultrafast magnetization reversal previously believed impossible is the combined result of femtosecond laser heating of the magnetic system to just below the Curie point and circularly polarized light simultaneously acting as a magnetic field. The direction of this opto-magnetic switching is determined only by the helicity of light. This finding reveals an ultrafast and efficient pathway for writing magnetic bits at record-breaking speeds.
RESUMEN
Subpicosecond magnetization reversal is experimentally demonstrated by ultrafast heating of a ferrimagnet across its compensation points, under an applied magnetic field. While the reversal is initiated by crossing the magnetization compensation temperature, the short reversal time is related to the angular momentum compensation, where the dynamics of the system is highly accelerated owing to the divergence of the gyromagnetic ratio. These results demonstrate the feasibility of subpicosecond magnetization reversal previously believed impossible.