Spatial imaging of the spin Hall effect and current-induced polarization in two-dimensional electron gases

Spin–orbit coupling in semiconductors relates the spin of an electron to its momentum, and provides a pathway for electrically initializing and manipulating electron spins for applications in spintronics1 and spin-based quantum information processing2. This coupling can be regulated with quantum confinement in semiconductor heterostructures through band-structure engineering. Here we investigate the spin Hall effect3,4 and current-induced spin polarization5,6 in a two-dimensional electron gas confined in (110) AlGaAs quantum wells using Kerr rotation microscopy. In contrast to previous measurements7,8,9,10, the spin Hall profile shows complex structure and the current-induced spin polarization is out-of-plane. The experiments map the strong dependence of the current-induced spin polarization to the crystal axis along which the electric field is applied, reflecting the anisotropy of the spin–orbit interaction. These results reveal opportunities for tuning a spin source using quantum confinement and device engineering in non-magnetic materials.