Anisotropic spin splitting in InGaAs wire structures

We report anisotropic spin splitting in gate-fitted InGaAs wires along different crystal orientations. Anisotropic magnetoconductance minima reflecting spin splitting is observed by decreasing wire width at the same carrier density. Anisotropy of spin splitting is reduced by applying negative gate voltages, while the strength of spin splitting is enhanced in the present InGaAs wire structures. This gate voltage dependence of spin splitting shows qualitative agreements with the theoretical calculations taking both Rashba SOI and Dresselhaus SOI into account.