The formation of bound states and the conductance modulation on 0.7 anomaly in a quantum wire

Abstract

The electron transport in a short quasi-1D quantum wire is studied. In addition to the conductance quantization, several resonances are observed. Two of the resonances appear as extra plateaus below 2e(2)/h. A gate voltage offset is used to tune the local potential of the quantum wire. A robust resonance is seen and the resonances evolve continuously with respect to the offset. The conductance has opposite responses to temperature in successive regions of gate voltage V(g). In the source-drain bias spectroscopy, two more conductance peaks are observed in addition to the Zero-Bias-Anomaly. The locations of the extra peaks evolve with respect to V(g) showing a pattern similar to that in a quantum dot. We suggest that a bound state forms in the quantum wire. The prominent 0.7 anomally in our quantum wire is recognized as the residue of conductance resonance.