Single shot all optical switching of intrinsic micron size magnetic domains of a Pt/Co/Pt ferromagnetic stack

We demonstrate that the magnetization reversal in a ferromagnetic Pt/Co/Pt stack can be induced by a single femtosecond laser pulse. We find that the size of the switched spot is comparable to the size of the intrinsic magnetic domains. It requires an absorbed energy density of $\sim$4 mJ.cm$^{-2}$, beyond which the excited spot fragments into a multidomain structure. The switching process occurs back and forth with subsequent laser pulses and it is helicity-independent. Furthermore, the dynamics of the magnetization reversal occurs in a timescale less than one microsecond. These results suggest that all optical switching in ferromagnetic films requires to match the laser spot with the specific domain sizes.