Probe of coherent and quantum states in narrow-gap semiconductors in the presence of strong spin-orbit coupling

In light of the growing interest in spin-related phenomena and devices, there is now a renewed interest in the science and engineering of narrow gap semiconductors. They offer several scientifically unique electronic features such as a small effective mass, a large g-factor, a high intrinsic mobility, and large spin-orbit coupling effects. Our studies have been focused on probing and controlling the coherent and quantum states in InSb quantum wells and InMnAs ferromagnetic semiconductors. Our observations are providing new information regarding the optical control of carriers and spins in these material systems. We demonstrated the generation of spin polarized photo-current in an InSb QW where a non-equilibrium spin population has been achieved by using circularly polarized radiation. In addition, the differential transmission measurements in InSb QWs demonstrated that the initial distribution function strongly influences the carrier relaxation dynamics. We employed the polarization-resolved differential transmission as well as the MOKE measurements to provide information on the spin relaxation dynamics in MOVPE grown InMnAs. Our measured T₁ is comparable to the reported measurements in MBE grown InMnAs and several time resolved measurements on InAs.