  Ultrafast laser-induced magnetic switching in rare earth, transition metal
ferrimagnetic alloys has recently been reported to occur by ultrafast heating
alone. Using atomistic simulations and a ferrimagnetic Landau-Lifshitz-Bloch
formalism, we demonstrate that for switching to occur it is necessary that
angular momentum is transferred from the longitudinal to transverse
magnetization components. This dynamical path leads to magnetization switching
and subsequent ultrafast precession caused by the inter-sublattice exchange
field on the nanoscale.
