Temperature dependence of spin transport by dynamic quantum dots

Electron spins in an undoped quantum well are transported using dynamic quantum dots (DQDs) formed by the piezoelectric potential of surface acoustic waves. The temperature dependence of the coherence length of electron spins during transport is investigated using spatially resolved photoluminescence. For temperatures between 4.2 and 20 K, the spin coherence length, which is proportional to the spin coherence lifetime, remains constant at approximately 100 μ m. This results from the ability of the DQDs to confine the spins within a small area (1 μ m ×× 1 μ m to 2 μ m ×× 2 μ m) during transport and reduce the temperature dependence associated with D’yakonov-Perel’ (DP) spin scattering. At 30 K, the electron spin coherence length rapidly decreases as the DP mechanism becomes dominant because of the higher thermal velocity on the Fermi surface.