Large Rashba Splitting in InAs Quantum Wells due to Electron Wave Function Penetration into the Barrier Layers

TLDR

The study reports zero‑field spin splitting in two‑dimensional electron systems. The Rashba parameter in the SAQW rises with electron density and can be tuned by a factor of ~2 via a front gate, with barrier‑penetration of the envelope wave function driving the spin‑orbit interaction. Applying a positive back‑gate voltage induces pronounced Rashba splitting in the SAQW, suggesting potential for high‑speed spintronic devices.

Abstract

We report on zero-field spin splitting of two-dimensional electron systems. Though absent in the unbiased InAs square asymmetric quantum well (SAQW), the Rashba splitting becomes pronounced by applying a positive back-gate voltage. In our SAQW, the Rashba parameter alpha increases with electron density and is tuned by a factor of about 2 using an additional front gate without charging the well. We argue that the band-edge profile provides the important contribution for spin-orbit interaction due to barrier penetration of the envelope wave function. This mechanism can provide the potential for high speed implementation in spintronics.