Fast switching of magnetization in the ferromagnetic semiconductor (Ga,Mn)(As,P) using nonequilibrium phonon pulses

We use short acoustic pulses to induce a fast irreversible switching of the magnetization orientation in a layer of (Ga,Mn)(As,P). The pulses are generated by femtosecond optical excitation of a metal transducer film and travel ballistically through the sample. We show that the switching is triggered by incoherent acoustic phonons, occurs through domain-related processes, and is concluded in ∼35 ns. We suggest that the mechanism behind the switching involves the holes in the material being heated due to their coupling to the phonons.