AC response of an atomic tunnel junction

Abstract

By combining density functional analysis with the solution of a three-dimensional quantum scattering problem, and applying appropriate ac transport theory, we investigated the ac transport response of Si atomic tunnel junctions in the resonance tunneling regime. Our results show that transmission channels of both the leads and the atomic section contribute to the dynamic conductance. The ac response is found to be determined by the average channel transmission weighted by the corresponding density of states, explaining a counterintuitive result that at resonance tunneling the ac response may be capacitivelike. As the ac frequency is increased, the resonance peak of dynamic conductance can be split into two, a phenomenon that can be explained analytically.