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Differential conductance of a saddle-point constriction with a time-modulated gate-voltage

C. S. Tang·C. S. Chu
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Abstract

The effect of a time-modulated gate-voltage on the differential conductance $G$ of a saddle-point constriction is studied. The constriction is modeled by a symmetric saddle-point potential and the time-modulated gate-voltage is represented by a potential of the form $V_{0} θ(a/2-|x-x_{c}|) \cos (ωt)$. For $\hbarω$ less than half of the transverse subband energy level spacing, gate-voltage-assisted (suppressed) feature occurs when the chemical potential $μ$ is less (greater) than but close to the threshold energy of a subband. As $μ$ increases, $G$ is found to exhibit, alternatively, the assisted and the suppressed feature. For larger $\hbarω$, these two features may overlap with one another. Dip structures are found in the suppressed regime. Mini-steps are found in the assisted regime only when the gate-voltage covers region far enough away from the center of the constriction.

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C. S. Tang, C. S. Chu. 2006-03-21. Differential conductance of a saddle-point constriction with a time-modulated gate-voltage. https://doi.org/10.1016/s0921-4526(98)00468-2

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