Gate-controlled Persistent Spin Helix State in Materials with Strong Spin-Orbit Interaction

Abstract

In layered semiconductors with spin-orbit interaction (SOI) a persistent spin helix (PSH) state with suppressed spin relaxation is expected if the strengths of the Rashba and Dresselhaus SOI terms, α and β, are equal. Here we demonstrate gate control and detection of the PSH in two-dimensional electron systems with strong SOI including terms cubic in momentum. We consider strain-free InGaAs/InAlAs quantum wells and first determine a ratio α/β ≃ 1 for non-gated structures by measuring the spin-galvanic and circular photogalvanic effects. Upon gate tuning the Rashba SOI strength in a complementary magneto-transport experiment, we then monitor the complete crossover from weak antilocalization via weak localization to weak antilocalization, where the emergence of weak localization reflects a PSH type state. A corresponding numerical analysis reveals that such a PSH type state indeed prevails even in presence of strong cubic SOI, however no longer at α = β.

Nonlinear Anomalous Hall Effect and Negative Magnetoresistance in a System with Random Rashba Field

“…Moreover, our effect is purely classical and not related to NMR in the weak localization regime. [26,27] Summary. We have calculated the anomalous Hall conductivity and the magnetoresistance of 2D electron systems due to scattering from spatial fluctuations of Rashba spin-orbit interaction.…”