Robustness of spin coherence of the exciton bound to neutral donor states in multilayer system

TL;DR

This study demonstrates the robustness of spin coherence in excitons bound to neutral donors in multilayer GaAs/AlGaAs quantum wells, maintaining long coherence times up to 250 K despite temperature-induced dephasing.

Contribution

It provides new insights into the temperature resilience of spin coherence in excitonic systems, highlighting mechanisms affecting spin dephasing and g-factor variation in multilayer quantum wells.

Findings

Spin coherence persists up to 250 K with T2* > 14 ns.

Temperature causes a significant reduction in spin dephasing time, nearly 98%.

Spin dynamics depend on magnetic field and pump power.

Abstract

We address the temperature influence on the precessional motion of electron spins under transverse magnetic field, studied in a GaAs/AlGaAs triple quantum wells, using pump-probe Kerr rotation. In the presence of an applied in-plane magnetic field the TRKR measurements show the robustness of carrier's spin polarization against temperature which can be easily traced in an extended range up to 250 K. By tuning the pump-probe wavelength to the exciton bound to a neutral donor transition, we observed a remarkably long-lasting spin coherence (with dephasing time T2* > 14 ns) limited by the spin hopping process and exchange interaction between the donor sites as well as the ensemble spread of g-factor. The temperature dependent spin dephasing time revealed a double linear dependence due to the different relaxation mechanisms active at respective temperature ranges. We observed that the increase of sample temperature from 5 K to 250 K, leads to a strong T2* reduction by almost 98%/97% for the excitation wavelengths of 823/821 nm. Furthermore, we noticed that the temperature increase not only causes the reduction of spin lifetime but can also lead to the variation of electron g-factor. Additionally, the spin dynamics was studied through the dependencies on the applied magnetic field and optical pump power.