Correlation field analysis of the influence of device geometry and bulk disorder on electron interference in quantum wires

We analyze the magnetic field dependence of the correlation field B_c of universal conductance fiuctuations (UCF), observed in GaAs/AlGaAs quantum wires. At sufficiently high magnetic fields, the Landau level quantization is resolved, and B_c is found to increase as a power law of magnetic field with an exponent which depends sensitively upon temperature. We show that this behavior results from a change in the nature of the (zero field) phase-coherent region for electron interference in the quantum wire; at high temperatures the phase-breaking length is less than the width, and the region is determined by the bulk impurities, while at lower temperatures, it is strongly influenced by the boundaries of the wire. We compare our results with recent theoretical predictions for the UCF at high magnetic fields, and show that the correlation analysis field provides a valuable tool for analyzing electron interference in quantum wires.