  Hole spin dephasing time due to the D'yakonov-Perel' mechanism in $p$-type
GaAs (100) quantum wells with well separated light-hole and heavy-hole bands is
studied by constructing and numerically solving the kinetic spin Bloch
equations. We include all the spin-conserving scattering such as the
hole-phonon and the hole-nonmagnetic impurity as well as the hole-hole Coulomb
scattering in our calculation. Different effects such as the temperature, the
hole density, the impurity density and the Rashba coefficient on the spin
dephasing are investigated in detail. We also show that the Coulomb scattering
makes marked contribution to the spin dephasing. The spin dephasing time can
either increase or decrease with temperature, hole/impurity density or the
inclusion of the Coulomb scattering depending on the relative importance of the
spin-orbit coupling and the scattering. It is also shown that due to the
different spin-orbit coupling strengthes, many spin dephasing properties of
holes are quite different from those of electrons.
