  Optically detected magnetic resonance (ODMR) is a useful technique for
studying interactions between local spins (magnetic ions) and carrier gas. We
present the ODMR study of single (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) with
the hole gas. We observe different characteristics of the ODMR signals obtained
simultaneously using the optical signals of neutral and positively charged
exciton. From that, we infer an existence of local fluctuations of carrier gas
density resulting in separate populations of Mn$^{2+}$ ions. At the same time,
the shape of the ODMR signal contains information about the temperature of the
magnetic ions involved in the absorption of the MW. Studying it in detail
provides even more information about the interactions with charge carriers. In
the QW, two separate ensembles of ions are thermalized differently in the
presence of carriers.
