Anomalous magnetoresistance peak in quantum wires: Evidence for boundary-scattering mechanisms

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Abstract
We present a combined experimental and theoretical investigation of the low-temperature magnetoresistance of quantum wires. A remarkable experimental feature is an anomalous resistance maximum at low magnetic fields related to scattering at wire boundaries. Theoretically, the influence of boundary scattering on magnetoresistance is calculated on the basis of the Kubo formula in the self-consistent Born approximation. Experimental and theoretical results are in good agreement in the whole magnetic-field range up to 5 T, including oscillations due to depopulation of one-dimensional subbands. Deviations from the classical linear dependence of the maximum position on inverse wire width in narrow quantum wires are explained by the influence of transversal quantization of the electronic states. The analysis of the difference between maximum resistance and zero-field resistance leads to a quadratic dependence on inverse wire width, in agreement with experiment. From the fit of the experimental data, we estimate the width of the disturbed regions at wire boundaries to be of the order of 10 nm.

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