Energy transfer from photocarriers into the magnetic ion system mediated by a two-dimensional electron gas in (Cd,Mn)Te/(Cd,Mg)Te quantum wells

An efficient energy-transfer channel from photocarriers to the Mn spin syst em via a two-dimensional electron gas (2DEG) in n-type modulation-doped Cd0 .99Mn0.01Te/Cd0.76Mg0.24Te quantum wells has been found. The energy relaxat ion of photoexcited carriers is assumed to cause heating of the electron ga s, which subsequently leads to an increase of the temperature of the Mn spi n system. The mechanism of the energy transfer from the 2DEG to the Mn syst em involves a spin-Rip scattering process originating in a strong electron- Mn exchange interaction. We have observed a suppression of the Mn heating w ith an increasing magnetic field which results in unusual energy shifts of the exciton, and trion features seen both in the photoluminescence and in r eflectivity spectra. A theoretical model has been developed which is in a g ood agreement with experimental results. In the framework of this model we also analyze the details of the dependence of Mn-ion heating on the electro n concentration and on the magnetic ion content.