  We propose a model of magnetic polaron formation in semiconductor quantum
dots doped with magnetic ions. A wetting layer serves as a reservoir of
photo-generated holes, which can be trapped by the adjacent quantum dots. For
certain hole densities, the temperature dependence of the magnetization induced
by the trapped holes is reentrant: it disappears for some temperature range and
reappears at higher temperatures. We demonstrate that this peculiar effect is
not an artifact of the mean field approximation and persists after statistical
spin fluctuations are accounted for. We predict fingerprints of reentrant
magnetic polarons in photoluminescence spectra.
