Spin-Conserving Tunneling of Excitons in Diluted Magnetic Semiconductor Double Quantum Wells

Spin polarization in carrier tunneling was studied in double quantum wells by the polarized photoluminescence-excitation spectroscopy. The double quantum wells consist of a diluted magnetic quantum well of Zn0.77Cd0.15Mn0.08Se and a nonmagnetic quantum well of Zn0.82Cd0.18Se. Efficient spin-conserving tunneling of an exciton as an entity was observed from the nonmagnetic quantum well to the magnetic well. The spin-reversing tunneling was suppressed by two orders of magnitude in high magnetic field. The spin-conserving tunneling time was determined as 20 ps by time resolved photoluminescence measurement.