Single picojoule pulse switching of magnetization in ferromagnetic (Ga,Mn)As

The recently demonstrated photoinduced reduction of the coercive field in (Ga,Mn)As is shown to display a pronounced increase in efficiency when triggered by short laser pulses. This is due to the relaxation timescale of the effect that is measured to be about 1.5 ns. In addition, a single 100-fs-pulse with only 80 pJ of energy is found to be sufficient to write a magnetic domain.