Experimental demonstration of resonant spin-orbit interaction effect

We investigated the spin lifetime in gate-fitted InGaAs narrow wires by magnetotransport measurement. By applying positive gate bias voltage, the spin lifetime in narrow wires became more than one order longer than those obtained from a Hall bar sample with two-dimensional electron gas. By comparison with a theoretical model of the quasi one-dimensional transport, it is found that this enhancement of spin lifetime in gated wires is due to dimensional confinement and resonant spin-orbit interaction effect by gate bias modulation of the Rashba spin-orbit interaction. Spin relaxation due to the cubic Dresselhaus term is negligible in the present InGaAs wires.