Semimagnetic Resonant Tunneling Diodes for Electron Spin Manipulation

Abstract : Recently, efficient electrical injection of spin polarized electrons into GaAs bas been accomplished by using a semimagnetic II-VI single layer, namely BeMnZnSe, as a spin aligner. In such spin aligner materials. the orientation of the electron spins can only be controlled by varying the magnetic field. Here, we introduce an approach aiming at manipulating spins by an external voltage. For that we developed BeTe/ZnMnSe/BeTe semimagnetic resonant tunneling diodes as a spin injector into nonmagnetic III-V material. By changing the resonance condition from a spin-up to spin-down Zeeman level, it should be possible to actually switch from one spin orientation to the other. An AlGaAs/GaAs/AlGaAs p-i-n Light Emitting Diode was used to detect the efficiency of the spin injection, because the circular polarization of the electroluminescence is a direct measure of the spin polarization of the injected electron current. Although no spin-splitting of the bound electron states in the ZnMNSe quantum well could be observed in current-voltage-measurements. electroluminescence from the LED revealed a high circular polarization of up to 70%, indicating a strongly spin-polarized electron current. The use of a semimagnetic RTD as a spin-switch device would represent a further important step towards spin manipulation in semiconductors.