Weak localization in ${\mathrm{Al}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ $p$-type quantum wells

We have experimentally investigated the weak-localization magnetoresistance in an ${\mathrm{Al}}_{0.5}{\mathrm{Ga}}_{0.5}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ $p$-type quantum well. The peculiarity of such systems is that spin-orbit interaction is strong. On the theoretical side it is not possible to treat the spin-orbit interaction as a perturbation. This is in contrast to all prior investigations of weak localization. In this paper we compare the experimental results with a newly developed diffusion theory, which explicitly describes the weak-localization regime when the spin-orbit coupling is strong. The spin relaxation rates calculated from the fitting parameters were found to agree with theoretical expectations. Furthermore, the fitting parameters indicate an enhanced phase-breaking rate compared to theoretical predictions.