Spin flip excitations in doped CdMnTe two-dimensional electron gases using terahertz time-domain spectroscopy
Résumé
n recent years, the scientific community has sought to better understand the dynamics of spins in semiconductors. Such an interest was driven by the foreseen possibility of using novel materials combining semiconducting with magnetic properties. These devices, called semi-magnetic semiconductors, could then be implemented in optoelectronic applications where information would be stored on spins. CdMnTe is promising material for such applications and its semi-magnetic properties are being extensively investigated. Spin wave excitations and single particle spin flips were investigated in doped CdMnTe two-dimensional electron gases (2DEG) using Raman spectroscopy under a static magnetic field. These experiments have shown the excitation energies and dispersion of the collective and individual response of spins, which happen in the THz spectral range. Terahertz time-domain spectroscopy (TDS) is a convenient tool to directly investigate intersubband electronic transitions. This technique allows the measurement of the phaseresolved transient THz field emitted by a photoconductive antenna and sent through a sample. Terahertz TDS experiments are expected to give more accurate estimates of the resonance frequencies of spins because they do not generate holes unlike Raman spectroscopy experiments. Furthermore, it would be possible to probe the relaxation times of these spin excitations using pump-probe experiments in the future.