Anomalous anti-Stokes scattering signal as an indicator of macrofilled magnetoexciton levels in the quantum Hall effect regime

The Raman study of strongly interacting two-dimensional electron systems based on ZnO/MgZnO has revealed an anomalously intense spectral line of the anti-Stokes component of the spin exciton. This line is manifested near the filling factor $\nu = 2$ at the ferromagnetic ordering of the spin subsystem, whereas it is not observed at the paramagnetic ordering. It has been shown that this line can be attributed to the formation of an ensemble of long-lived collective excitations in the ferromagnetic phase at a filling factor of $\nu = 2$.