  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.
