Ballistic transport in one dimension: additional quantisation produced by an electric field

Abstract

Experimental evidence is presented for the appearance of new plateaux in the differential conductance of a ballistic 1D channel in the high DC bias regime. In zero magnetic field, the authors observe steps in the differential conduction of e²/h, as opposed to the conventional value of 2e²/h for a spin-degenerate 1D subband. The new plateaux are found to be at quantised values to an accuracy of a few per cent and are described well by a model that assumes the bias is dropped symmetrically in the 1D channel. In addition, all the plateaux disappear with increasing DC voltage bias which can be explained in terms of an enhancement of the tunnelling probability. The same effects persist in a transverse magnetic field and the authors are able to calculate subband spacings as a function of the applied magnetic field.