Phonon-Induced Efficient Transfer of Spin-Polarized Excitons in Diluted Magnetic Semiconductor Double Quantum Wells

Abstract

We demonstrate the efficient transfer of spin-polarized excitons in diluted magnetic semiconductor (DMS) double quantum wells (QWs), where the spin-polarized excitons tunnel from the bottom of a non magnetic QW into a DMS-QW across a tunneling barrier and subsequently relax to the exciton ground state in the DMS-QW with phonon emissions. The exciton-transfer time decreases significantly when the exciton energy difference between both wells is equal to the energy of one longitudinal optical (LO) phonon. This observation indicates that the exciton spin transfer can be accelerated with the conservation of the spin polarization by the energy relaxation with the LO-phonon emission immediately after the tunneling.