  We have studied quantum-well-confined holes based on the Luttinger-model
description for the valence band of typical semiconductor materials. Even when
only the lowest quasi-two-dimensional (quasi-2D) subband is populated, the
static spin susceptibility turns out to be very different from the universal
isotropic Lindhard-function lineshape obtained for 2D conduction-electron
systems. The strongly anisotropic and peculiarly density-dependent spin-related
response of 2D holes at long wavelengths should make it possible to switch
between easy-axis and easy-plane magnetization in dilute magnetic quantum
wells. An effective g factor for 2D hole systems is proposed.
