Nonlinear conductance of quantum point contacts

L. P. Kouwenhoven; B. J. van Wees; C. J. P. M. Harmans; J. G. Williamson; H. van Houten; C. W. J. Beenakker; C. T. Foxon; J. J. Harris

doi:10.1103/PhysRevB.39.8040

Rapid Communication

Nonlinear conductance of quantum point contacts

L. P. Kouwenhoven, B. J. van Wees, C. J. P. M. Harmans, J. G. Williamson, H. van Houten, C. W. J. Beenakker, C. T. Foxon, and J. J. Harris

Phys. Rev. B 39, 8040(R) – Published 15 April 1989

Abstract

The conductance of ballistic quantum constrictions in a two-dimensional electron gas has been studied experimentally as a function of the applied voltage. Large nonlinearities are found in the current-voltage characteristics. We give a simple model, which explains the main features of the nonlinear conductance. Breakdown of the conductance quantization occurs when the number of occupied one-dimensional subbands becomes unequal for the two velocity directions. A critical voltage is found for the breakdown, which is equal to the subband separation at the Fermi level.