Giant Photoinduced Excitonic Faraday Rotation inCdTe/Cd1−xMnxTeMultiple Quantum Wells

We report a giant photoinduced Faraday rotation in a $\mathrm{CdTe}/{\mathrm{Cd}}_{1-x}{\mathrm{Mn}}_x\mathrm{Te}$ multiple quantum well structure when the laser frequency is tuned close to the fundamental excitonic transition of the quantum well and saturation sets in. At the same time we observe stimulated emission and buildup of magnetization through photon spin recycling in the presence of a magnetic field which was analyzed by a time-resolved linearly polarized pump and probe technique. The magnetization buildup is also seen in the absence of the seeding magnetic field and by using a circularly polarized pump beam.