The effect of current, illumination and contact nature on equilibration between bulk and edge current-carrying states

The form of the high-field spin-resolved Shubnikov-de Haas resistance maxima in a high-mobility GaAs-(Ga.A1)As heterojunction 2D electron gas is shown to be strongly dependent on current, illumination time and the nature of the voltage contacts.The effects of increasing current and illumination time are very similar, with both reducing the influence of the contact nature.The similarity is attributed to a common modification of the edge potential in the device due to a change in the device electrostatics.At saturation illumination the current dependence is found to be wholly absent.The edge-bulk scattering length calculated from the theory of the current dependence of the maxima is found to be strongly dependent on the type of voltage contact used, indicating that this value does not reflect a fundamental bulk property.We also Observe contact-specific fine structure in the N = 1 high-field maximum, which is attributed to fluctuations in the transmission coefficients of the voltage probes.