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

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 2e²/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 anomaly in our quantum wire is recognized as the residue of conductance resonance.