Spin–lattice relaxation in semimagnetic CdMnTe/CdMgZnTe quantum wells with a two-dimensional hole gas tuned by optical excitation

We measure the spin–lattice relaxation time of Mn ions in Cd1−xMnxTe/Cd0.66Mg0.27Zn0.07Te (x=0.0035) semimagnetic quantum wells in the presence of a two-dimensional hole gas (2DHG) with sheet densities up to 3×1010 cm−2. We show that the presence of a 2DHG reduces the spin–lattice relaxation time by more than one order of magnitude. This reduction is much stronger than a similar effect induced by the presence of a two-dimensional electron gas, which is due to the heavier hole mass and stronger p–d interaction for holes with Mn ions. We demonstrate experimentally the possibility to tune the spin–lattice relaxation time by varying the density of the 2DHG through above-barrier photoexcitation.