Spin transport in a tubular two-dimensional electron gas with Rashba spin-orbit coupling

We investigate the properties of local spin current and local spin density in a tubular two-dimensional electron gas system with Rashba spin-orbit coupling. To evaluate the spatial distribution of the spin-related quantities in both equilibrium and nonequilibrium cases, we derive the tubular version of tight-binding model and then employ the Landauer-Keldysh formalism. Our work reveals that the tubular geometry effect can cause spin-orbit-induced phenomena very different from those in a planar sample. In particular, a persistent spin current circulating in the tubular system is found to be robust against the disorder, thus suggesting its observability. In spite of the absence of spin accumulation, the spin Hall current can still arise and even circulate in the tubular sample. Moreover, a spin-independent impurity will induce distinctive spin accumulation patterns around the impurity, which may serve as a novel mechanism to control electron spins by arranging the impurities for spintronic devices.