Measurement of anisotropic spin-orbit interaction in a two-dimensional electron gas using ballistic spin resonance

We report the observation of strongly anisotropic spin-orbit interaction in a 2D electron gas (2DEG) along the [110] and [1$\bar{1}$0] crystal axes of a GaAs/AlGaAs triangular well, indicating that the Rashba and Dresselhaus contributions to the interaction are closely matched in this structure. Spin relaxation due to spin-orbit interaction is probed using ballistic spin resonance (BSR) [1] in a narrow 2DEG channel: an oscillating spin-orbit field is induced by high-frequency bouncing of free electrons between the channel walls, which leads to rapid relaxation when the bouncing frequency matches the Larmor frequency in a static external magnetic field. Drastically different BSR strengths are observed for channels fabricated along the two crystal axes, from which the magnitudes of Rashba and Dresselhaus contributions can be extracted. \newline [1] S. M. Frolov et al., Nature 458, 868-871(2009)