Spin Control in Diluted Magnetic Ion Doped Nano-Wire Structures
Seiji NAGAHARA, Takashi KITA, Osamu WADA and Henri MARIETTE
Abstract:We have studied anisotropic exchange interaction in (CdTe)0.5(Cd0.75Mn0.25Te)0.5 tilted superlattices fabricated by fractional monolayer growth onto a 1-degree off vicinal surface of Cd0.74Mg0.26Te (001). The (CdTe)0.5(Cd0.75Mn0.25Te)0.5 tilted superlattices have been confirmed by polarized photoluminescence to be equivalent to compositionally modulated quantum wires consisting of CdTe-rich and Cd0.75Mn0.25Te-rich wires. The Stokes shift for the CdTe-rich wires is remarkable at less than 10 K. The large Stokes shift is due to exciton-magnetic polaron formation and non-magnetic localization. The exciton magnetic polaron formation is a result of the exchange interaction between excitons and Mn ions. The exchange interaction causes the large Zeeman shift of the CdTe-rich wires. The Zeeman shift depends on the direction of the magnetic field in the (001) plane; the Zeeman shift in the magnetic field parallel to the wire direction is smaller than that in the perpendicular field. We demonstrate reorientation of hole spins in the parallel magnetic field by polarized magneto-photoluminescence measurements. The reorientation of the hole spins causes the valence-band mixing, which results in the small Zeeman shift in the parallel magnetic field. Key Words:Compositionally modulated quantum wires, Exciton magnetic polaron, Anisotropic exchange interaction, Reorientation of the hole spins