Observation of the zero-field spin splitting of the second subband in an inverted In0.53Ga0.47As/In0.52Al0.48As heterostructure

A gated inverted In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As quantum well is studied via magneto transport. By analysing the gate-voltage-dependent beating pattern observed in the Shubnikov-de Haas oscillation, we determine the gate voltage (or electron concentration) dependence of the spin-orbit coupling parameter α. Our experimental data and their analysis show that the band nonparbolicity effect cannot be neglected. For electron concentrations above 2×10 12 cm −2 , it causes a reduction of α up to 25%. We report for the first time the α value for the second subband.