sub-100 ps all-optical magnetic switching by passive wavefront shaping

Abstract The recently discovered magnetization reversal driven solely by a femtosecond laser pulse hasbeen shown to be a promising way to record information at record breaking speeds. Seeking toimprove the recording density has raised intriguing fundamental question about the feasibility tocombine the ultrafast temporal with sub-wavelength spatial resolution of magnetic recording. Herewe report about the rst experimental demonstration of sub-di raction and sub-100 ps all-opticalmagnetic switching. Using computational methods we reveal the feasibility of sub-di raction mag-netic switching even for an unfocused incoming laser pulse. This e ect is achieved via structuringthe sample such that the laser pulse experiences a passive wavefront shaping as it couples andpropagates inside the magnetic structure. Time-resolved studies with the help of photo-emissionelectron microscopy clearly reveal that the sub-wavelength switching with the help of the passivewave-front shaping can be pushed into sub-100 ps regime.