Negative differential conductance in a quantum dot and possible application to ESR detection

Abstract

We propose a new scheme of detecting electron spin resonance (ESR) using a single quantum dot (QD). Suppose up-spin (down-spin) electrons can only transport through the ground (excited) state with a large (small) tunnel coupling. Negative differential conductance (NDC) appears when both states enter the transport window because of dynamical population of the excited state. This NDC can be restored by ESR when the dot-lead coupling of the ground and excited states is asymmetric between the two tunnel barriers. We first experimentally characterize the conditions of NDC, which appears when edge states are formed in the leads, to derive the parameters of tunnel coupling. We finally calculate the modulation of QD current induced by ESR to lift the NDC characteristic. © 2009 IOP Publishing Ltd.