On the control of optical spin injection by tuning the band gap offset in magnetic/non-magnetic hybrid structure

Abstract

Abstract We investigate, using a heterostructure consisting of Cd 0.97 Mn 0.03 Te/Cd 0.98 Mg 0.02 Te layers the optical spin injection process from the Cd 0.97 Mn 0.03 Te spin aligner into the non-magnetic Cd 0.98 Mg 0.02 Te neighboring layer. We find that the spin injection process can be controlled by an external magnetic field (~0.5 T). Utilizing the circular polarization of the photoluminescence emitted from the Cd 0.98 Mg 0.02 Te layer, we monitor the injected spins of the carriers. As the magnetic field is increased, the degree of the circular polarization changes its sign from positive (with the σ + intensity dominating), indicating occurrence of the spin injection, to a negative value (with the σ − intensity dominating), indicating the inhibition of the spin injection. We study also the temperature dependence of the degree of the circular polarization of Cd 0.98 Mg 0.02 Te emissions at a fixed magnetic field, and thus of the injection efficiency.