Quantum transport in In0.75Ga0.25As quantum wires

In addition to quantized conductance plateaus at integer multiples of 2e2∕h, the differential conductance G=dI∕dV shows plateaus at 0.25(2e2∕h) and 0.75(2e2∕h) under applied source-drain bias in In0.75Ga0.25As quantum wires defined by insulated split gates. This observation is consistent with a spin-gap model for the 0.7 structure. Using a tilted magnetic field to induce Landau level crossings, the g factor was measured to be ∼9 by the coincidence method. This material, with a mobility of 1.8×105cm2∕Vs at a carrier density of 1.4×1011cm−2, may prove useful for further study of electron-electron interaction effects in quantum wires.