  The magnetization dynamics for ferrimagnets at the angular momentum
compensation temperature T_A is believed to be analogous to that for
antiferromagnets. We investigated the pulsed-laser-induced magnetization
dynamics in amorphous rare-earth transition-metal ferrimagnet films with a T_A
just above room temperature. For a low pulse fluence, the magnetization
precession frequency decreases as the applied magnetic field increases, whereas
for a higher pulse fluence, it increases as the applied field increases. The
result was well explained by the left-handed and right-handed precession modes
of the antiferromagnetic-like resonance at temperatures below and above T_A,
respectively, and the data were in agreement with the theoretical simulation.
The study demonstrated the experimental route to achieving antiferromagnetic
resonance in ferrimagnets using a pulsed laser.
