THEORY OF NONLINEAR TRANSPORT IN NARROW BALLISTIC CONSTRICTIONS

We present quantum-mechanical model calculations of nonlinear transport in narrow ballistic constrictions. We calculate the current and differential conductance g as functions of the applied voltage V0 and the electron Fermi energy EF. Nonlinear effects in g smooth out transmission resonances and shift and degrade the quantized ballistic conductance plateaus. Contrary to previous claims, we find that g does not develop additional plateaus between those quantized at 2ne2/h. At high V0 the current saturates at values strongly dependent on EF.. AE © 1990 The American Physical Society.