Zero-field spin splitting in a two-dimensional electron gas

The spin splitting in zero magnetic field which was recently reported in ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/${\mathrm{In}}_{0.52}$ ${\mathrm{Al}}_{0.48}$As heterostructures is analyzed with use of the inversion-asymmetry, or ${\mathit{k}}^3$, term and the interface spin orbit or Rashba term. Comparison with experimental data shows that Rashba term is the dominant spin-splitting mechanism in these samples. Zero-field spin splittings of 2.5–2.75 meV are deduced from the perpendicular-field data. Analysis of tilted-magnetic-field data gives g factors that lie between -2 and -3.