Coherent spin dynamics of an interwell excitons gas in GaAs/AlGaAs coupled quantum wells

TL;DR

This study investigates the spin dynamics of interwell excitons in GaAs/AlGaAs coupled quantum wells, revealing a collective phase with reduced spin relaxation rate indicating coherence below a critical temperature.

Contribution

It provides new insights into the collective exciton phase and its spin coherence properties in coupled quantum wells under electric fields.

Findings

Spin relaxation rate is strongly reduced in the collective phase.

Evidence of exciton phase coherence below a critical temperature.

Temperature dependence of spin relaxation supports collective behavior.

Abstract

The spin dynamics of an interwell excitons gas has been investigated in n-i-n GaAs/AlGaAs coupled quantum wells (CQWs). In these heterostructures the electron and the hole are spatially separated in neighboring quantum wells by a narrow AlAs barrier, when an electric field is applied. The time evolution kinetics of the interwell exciton photoluminescence has been measured under resonant excitation of the 1sHH intrawell exciton, using a pulsed tunable laser. The formation of a collective exciton phase in time and the temperature dependence of its spin relaxation rate have been studied. The spin relaxation rate of the interwell excitons is strongly reduced in the collective phase. This observation provides evidence for the coherence of the indirect excitons collective phase at temperatures below a critical $T_c$.