Relaxation mechanisms of the persistent spin helix

We study the lifetime of the persistent spin helix in semiconductor quantum wells with equal Rashba and linear Dresselhaus spin-orbit coupling strengths. In order to address the temperature dependence of the relevant spin relaxation mechanisms we derive and solve a semiclassical spin diffusion equation taking into account the effects of spin-dependent impurity scattering, cubic Dresselhaus spin-orbit coupling and electron-electron interactions. For the experimentally relevant regime we find that the lifetime of the persistent spin helix is mainly determined by the interplay of cubic Dresselhaus spin-orbit interaction and electron-electron interactions. We propose that even longer lifetimes can be achieved by generating a spatially damped spin profile instead of the persistent spin helix state