Imaging chiral Andreev reflection in the presence of Rashba spin-orbit coupling

TL;DR

This paper theoretically investigates how chiral Andreev edge states and spin-orbit interactions influence magnetic focusing in a 2D electron gas with superconducting contacts, revealing enhanced spin separation and detailed electron-hole trajectories.

Contribution

It introduces a theoretical model of chiral Andreev reflection in a Rashba spin-orbit coupled system, highlighting the impact on spin separation and transport properties.

Findings

Enhanced spin-split focal point separation scales with Andreev scattering events.

Distinct conductance features reveal electron-hole cyclotron paths.

Spin-orbit interaction causes carriers to follow different cyclotron orbits.

Abstract

In this work, we theoretically study transverse magnetic focusing in a two-dimensional electron gas with strong Rashba spin-orbit interaction when proximitized along its edge with a superconducting contact. The presence of superconducting correlations leads to the emergence of chiral Andreev edge states which -- within this weak magnetic field regime -- may be pictured as states following semiclassical skipping orbits with alternating electron-hole nature. The spin-orbit induced splitting of the Fermi surface causes these carriers to move along cyclotron orbits with different radii, allowing for their spatial spin separation. When Andreev reflection takes place at the superconducting lead, scattered carriers flip both their charge and spin, generating distinguishable features in the transport properties of the device. In particular, we report a notable enhancement of the separation between the spin-split focal points, which scales linearly with the number of Andreev scattering events at the anomalous terminal. We support our results by calculating conductance maps to arbitrary points in the sample that provide a complete image of the ballistic electron-hole cyclotron paths.