Optical polarization relaxation in ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$-based quantum wells: Evidence of the interface symmetry-reduction effect

We report on the measurement of the spin dynamics in ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}{\mathrm{A}\mathrm{s}-\mathrm{A}\mathrm{l}}_x{\mathrm{In}}_{1-x}\mathrm{As}$ and ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}-\mathrm{I}\mathrm{n}\mathrm{P}$ multiquantum wells, using a fs pump and probe experiment. We observe a large difference in the polarization relaxation times, which confirms the recently predicted role of the interface symmetry reduction.