Large spontaneous spin splitting in gate-controlled two-dimensional electron gases at normal $In0.75Ga0.25As/In0.75Al0.25As$ heterojunctions Available to Purchase

Amounts of spontaneous spin splittings were estimated from low-temperature magnetoresistances in two-dimensional electron gases created at $In0.75Ga0.25As/In0.75Al0.25As$ heterojunctions under a gate bias. Typical sheet electron densities and mobilities in the raw wafers were $∼1.0×1012/cm2$ and $2–5×105 cm2/V s$ at 1.5 K, respectively. A maximum spin-orbit coupling constant $αzero$ of $∼30(×10−12 eV m)$ was obtained for the van der Pauw sample. In gated Hall-bar samples, a decrease in the $αzero$ value with decreasing gate voltage $(Vg)$ was first confirmed in a normal heterojunction. The main origin for such a large $αzero,$ which is a few times larger than any previously reported, was found to be a structure-dependent so-called interface contribution in the Rashba term.