[15a-501-1~10] 10.4 半導体スピントロニクス・超伝導・強相関

▲ [15a-501-4] Origin of long-lived spin dynamics in undoped GaAs quantum wells

〇眞田 治樹¹、国橋 要司¹、田中 祐輔¹、後藤 秀樹¹、小野満 恒二¹、好田 誠²、新田 淳作²、寒川 哲臣¹ (1.NTT物性基礎研、2.東北大工)

キーワード：spin relaxation, spin orbit interaction, dark exciton

Finding a way to preserve spins in non-magnetic semiconductors is essential for future spin-based electronics. The spins of excitons have been widely explored because the polarization-dependent selection rule of inter-band optical transition provides rich information about their spins. However, the time scale on which we can measure the exciton spins is limited by the radiative lifetime, which is often less than 1 ns. In this report, we discuss the origin of the unexpectedly long decay time (>10 ns) of a Kerr rotation (KR) signal observed in an undoped GaAs quantum well (QW). We consider a probable cause of the observed long KR decay is the existence of spin-polarized dark excitons. Additional data also gave us the opportunity to discuss spin diffusion and spin-orbit interaction for the dark excitons, which have not previously been closely investigated. The ability to access the dark exciton spins might offer the possibility of memorizing quantum information in solid state systems.