  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 spintronics and spin-based quantum
information processing. This coupling can be regulated with quantum confinement
in semiconductor heterostructures through band structure engineering. Here we
investigate the spin Hall effect and current-induced spin polarization in a
two-dimensional electron gas confined in (110) AlGaAs quantum wells using Kerr
rotation microscopy. In contrast to previous measurements, the spin Hall
profile exhibits 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.
