is possible.

Magnetotransport in chalcogenide QWs
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### Low-field magnetotransport in DMS QWs

The first grown DMS QWs had usually low mobilities [@Scholl1995; @Smorchkova1997], which was caused mainly by poorly developed growth technology and in part by disorder introduced by magnetic ions. All of these QWs had similar features in magnetoresistance (MR) [@Scholl1993; @Smorchkova1996; @Smorchkova1997; @Andrearczyk2002], i.e.: (a) significant low-field positive MR and (b) high-field negative MR. Qualitatively the same MR behavior was observed in both perpendicular and parallel fields [@Smorchkova1997; @Andrearczyk2002], which points to the importance of the giant spin splitting in scattering processes. In 3D DMS such positive MR behavior was explained [@Sawicki1986] by the destructive effect of giant exchange-induced spin splitting on the quantum correction to conductivity in the weakly localized regime. The observed increase of the resistivity with lowering temperature indicated the formation of magnetic polarons (MPs) [@Wolff1988; @Dietl1982; @Dietl1983], ferromagnetic clouds of Mn ion spins that are polarized by a quasilocalized electron spin within its localization orbit. These MPs constitute centers of effective spin-disorder scattering that increases resistivity. Application of high magnetic field destroys MPs, and hence suppress scattering, which leads to the positive magnetoresistance. However, in modulation-doped QWs charged donors are removed from the 