Magnetization switching by ultrashort acoustic pulses

It is shown theoretically that a single a few picoseconds long acoustic pulse can reverse magnetization in a magneto-strictive material Terfenol-D. Following giant magneto-elastic changes of free energy density the magnetization vector is kicked out of a local in-plane energy mininum and decays into another minimum. For acoustic pulse duration significantly shorter than magnetization precession period ${\tau }_{ac}$<<$T_{prec}$, the switching threshold is determined by the {\it acoustic pulse area}, i.e. pulse integral in time domain, similar to coherent phenomena in optics. Simulation results are summarized in a magneto-acoustic switching diagram and discussed in the context of all-optical magnetization switching by circularly polarized light pulses.