Physical Review Letters 100,12 (2008)
We investigate effects of lateral confinement on spin splitting of energy levels in 2D hole gases grown on  GaAs. We found that lateral confinement enhances anisotropy of spin splitting relative to the 2D gas for both confining directions. Unexpectedly, the effective g factor does not depend on the 1D energy level number N for B parallel to[0 (1) over bar1] while it has strong N dependence for B parallel to[(2) over bar 33]. Apart from quantitative difference in the spin splitting of energy levels for the two orthogonal confinement directions, we also report qualitative differences in the appearance of spin-split plateaus, with nonquantized plateaus observed only for the confinement in the [0 (1) over bar1] direction. In our samples we can clearly associate the difference with anisotropy of spin-orbit interactions.
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