2D Rutherford-Like Scattering in Ballistic Nanodevices

TL;DR

This paper demonstrates that local depletion near a quantum ring's antidot can improve ballistic electron injection, with effects explained by a 2D Rutherford scattering analogy, supported by experiments and simulations.

Contribution

It introduces a novel analogy between Rutherford scattering and electron injection in quantum rings, revealing how local depletion enhances ballistic transport.

Findings

Local depletion near the antidot improves injection efficiency.

Charge accumulation can increase reflection and reduce transmission.

The effect scales with the ratio of perturbation strength to Fermi energy.

Abstract

Ballistic injection in a nanodevice is a complex process where electrons can either be transmitted or reflected, thereby introducing deviations from the otherwise quantized conductance. In this context, quantum rings (QRs) appear as model geometries: in a semiclassical view, most electrons bounce against the central QR antidot, which strongly reduces injection efficiency. Thanks to an analogy with Rutherford scattering, we show that a local partial depletion of the QR close to the edge of the antidot can counter-intuitively ease ballistic electron injection. On the contrary, local charge accumulation can focus the semi-classical trajectories on the hard-wall potential and strongly enhance reflection back to the lead. Scanning gate experiments on a ballistic QR, and simulations of the conductance of the same device are consistent, and agree to show that the effect is directly proportional to the ratio between the strength of the perturbation and the Fermi energy. Our observation surprisingly fits the simple Rutherford formalism in two-dimensions in the classical limit.