  We have studied ultrafast photoinduced demagnetization in GaMnAs via
two-color time-resolved magneto-optical Kerr spectroscopy. Below-bandgap
midinfrared pump pulses strongly excite the valence band, while near-infrared
probe pulses reveal sub-picosecond demagnetization that is followed by an
ultrafast ($\sim$1 ps) partial recovery of the Kerr signal. Through comparison
with InMnAs, we attribute the signal recovery to an ultrafast energy relaxation
of holes. We propose that the dynamical polarization of holes through $p$-$d$
scattering is the source of the observed probe signal. These results support
the physical picture of femtosecond demagnetization proposed earlier for
InMnAs, identifying the critical roles of both energy and spin relaxation of
hot holes.
