Electron Spin Flip by Antiferromagnetic Couplingbetween Semiconductor Quantum Dots

摘要

We have investigated magnetic coupling betweensemiconductor quantum dots. The antiferromagnetization process basedon the interdot exchange interaction has been directly observed usingtime-resolved spin-dependent photoluminescence measurements. Theantiferromagnetic order that proves the interdot exchange interactionenergy to be negative is found to exist at temperatures lower than 50-80 K.Electron spin flips at 80 ps after photoexcitation. The spin relaxation timeunder the antiferromagnetic order is extended to 10-12 ns, an order ofmagnitude longer than that in isolated quantum dots.