Controlling laser-induced magnetization reversal dynamics in a rare-earth iron garnet across the magnetization compensation point

The ultrafast manipulation of the magnetization using femtosecond laser pulses is of utmost importance for both fundamental physics and technological applications. Here, the authors investigated the laser-induced ultrafast magnetization dynamics in a rare-earth iron garnet over a broad temperature range including the magnetization compensation point T${}_{\mathrm{M}}$. They find that the heat energy resulting from exciting the phonon-assisted $d$-$d$ transitions induces large-amplitude magnetization dynamics at temperatures slightly below T${}_{\mathrm{M}}$. They also demonstrate that the speed and the amplitude of the magnetization dynamics can be controlled by tuning either the laser energy density or the amplitude of the external magnetic field. The obtained results are explained by a magnetization reversal process across T${}_{\mathrm{M}}$.