Scanning gate imaging in confined geometries

Abstract

This article reports on tunable electron backscattering investigated with the biased tip of a scanning force microscope. Using a channel defined by a pair of Schottky gates, the branched electron flow of ballistic electrons injected from a quantum point contact is guided by potentials of a tunable height well below the Fermi energy. The transition from injection into an open two-dimensional electron gas to a strongly confined channel exhibits three experimentally distinct regimes: one in which branches spread unrestrictedly, one in which branches are confined but the background conductance is affected very little, and one where the branches have disappeared and the conductance is strongly modified. Classical trajectory-based simulations explain these regimes at the microscopic level. These experiments allow us to understand under which conditions branches observed in scanning gate experiments do or do not reflect the flow of electrons.

7 pages, 5 figures

References in corpus (8)

• Quantum Transport in Semiconductor Nanostructures
• Coherent Branched Flow in a Two-Dimensional Electron Gas
• Imaging Fractal Conductance Fluctuations and Scarred Wave Functions in a Quantum Billiard
• A low-temperature dynamic mode scanning force microscope operating in high magnetic fields
• Operation characteristics of piezoelectric quartz tuning forks in high magnetic fields at liquid helium temperatures
• Interference of electrons in backscattering through a quantum point contact
• Scanning-gate-induced effects and spatial mapping of a cavity
• Locally induced quantum interference in scanning gate experiments

Cited by in corpus (9)

• Interference features in scanning gate conductance maps of quantum point contacts with disorder
• Scanning gate experiments: from strongly to weakly invasive probes
• Partial local density of states from scanning gate microscopy
• Energy Stability of Branching in the Scanning Gate Response of Two-Dimensional Electron Gases with Smooth Disorder
• Stable Branched Electron Flow
• Classical origin of conductance oscillations in an integrable cavity
• Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities
• Electron backscattering in a cavity: ballistic and coherent effects
• Imaging signatures of the local density of states in an electronic cavity