Imaging snake orbits at graphene n-p junctions

TL;DR

This paper investigates conductance oscillations along graphene n-p junctions in the quantum Hall regime, revealing how magnetic field and probe potential influence interference patterns and localized resonances.

Contribution

It provides a detailed analysis of conductance mapping and interference effects in graphene n-p junctions under quantum Hall conditions, highlighting the role of the Aharonov-Bohm effect.

Findings

Conductance oscillations are periodic with magnetic field and Fermi energy.

Localized resonances cause narrow conductance lines parallel to the junction.

Interference effects depend on probe potential and junction transparency.

Abstract

We consider conductance mapping of the snake-orbits confined along the n-p junction defined in graphene by the electrostatic doping in the quantum Hall regime. We explain the periodicity of conductance oscillations at the magnetic field and the Fermi energy scales by the properties of the n-p junction as a conducting channel. We evaluate the conductance maps for a floating gate scanning the surface of the device. In the quantum Hall conditions the currents flow near the edges of the sample and along the n-p junction. The conductance mapping resolves only the n-p junction and not the edges. The conductance oscillations along the junction are found in the maps with periodicity related to the cyclotron orbits of the scattering current. Stronger probe potentials provide support to localized resonances at one of the sides of the junction with current loops that interfere with the n-p junction currents. The interference results in a series of narrow lines parallel to the junction with positions that strongly depend on the magnetic field through the Aharonov-Bohm effect. The consequences of a limited transparency of finite width n-p junctions are also discussed.