conductive channel, thus the formation of MPs is less probable. Indeed in magneto-optical studies [@Smorchkova1998a; @Smorchkova1998b; @Kikkawa1998] no signatures of bound MP formation in DMS QWs have been found. It was debated that the existence of so-called free magnetic polarons — spin-dressed carrier states — may explain the experimental data [@Smorchkova1997; @Smorchkova1998b]. Strong, high-field, negative MR in DMS QWs, observed close to the metal-insulator transition [@Jaroszynski2007], was explained by the formation of ferromagnetic bubbles and corresponding electronic phase separation. At low temperatures, there is a competition between the insulating DMS phase characterized by antiferromagnetic interactions and the metallic phase which is governed by carrier-mediated ferromagnetic correlations [@Dietl2000]. Thus, ferromagnetic metallic bubbles are formed within a carrier-poor, magnetically disordered matrix. Such behavior resembles that of the colossal MR phenomenon observed in manganites [@Jin1994]. Low-field positive MR in DMS QWs is usually explained [@Smorchkova1996; @Smorchkova1997; @Smorchkova1998] by the quantum corrections to the conductivity originating from electron-electron interactions [@Lee1985; @Altshuler1985], modified by a giant spin splitting.

Magnetic impurities also affect transverse magnetotransport in DMS QWs, leading to the anomalous Hall effect (AHE) which occurs in all magnetic systems. Edwin Hall measured anomalously high “rotational coefficients” in nickel and cobalt [@Hall1881] almost a year 