Spin relaxation in a strongly correlated quantum Hall ferromagnet
The spin relaxation of a strongly correlated electron system hosted in a narrow AlAs quantum well is studied experimentally in the regime of the quantum Hall ferromagnet, i.e., near odd fillings of the integer quantum Hall effect. The relaxation rate is evaluated by analyzing the linewidth of the electrically detected electron-spin resonance. The measured spin dynamics is shown to undergo a radical modification in tilted magnetic fields. Increasing of the tilt angle resulted not only in the decrease of the relaxation time at the exact odd fillings by almost an order of magnitude, but also in the essentially different dependence of the relaxation rate on the filling factor at highest tilt angles. In the case of a perpendicular magnetic field the relaxation rate reached its minimal value near the exact odd filling and slowly increased when the filling factor ν was altered. In contrast, at large tilt angles relaxation turned out to be the fastest at some ν in close vicinity of the exactly odd number. The observed effects may be ascribed to the renormalization of the spin excitation spectra by the strong e-e interaction.