Giant and anisotropic enhancement of spin-charge conversion in double Rashba interface graphene-based quantum system

TL;DR

This study reports a 34-fold enhancement and anisotropy in spin-charge conversion in a graphene-based quantum system with a double Rashba interface, highlighting interface engineering's potential for advanced spintronic devices.

Contribution

It demonstrates a significant increase in spin-to-charge conversion efficiency using a graphene monolayer and reveals the role of interface asymmetry and Rashba effects, supported by first-principles theory.

Findings

34-fold increase in spin-to-charge conversion

Discovery of anisotropic spin conversion

Interface asymmetry drives enhancement

Abstract

The ever-increasing demand for efficient data storage and processing has fueled the search for novel memory devices. Spintronics offers an alternative fast and efficient solution using spin-to-charge interconversion. In this work, we demonstrate a remarkable thirty-four-fold increase in spin-to-charge current conversion when incorporating a 2D epitaxial graphene monolayer between iron and platinum layers by exploring spin-pumping on-chip devices. Furthermore, we find that the spin conversion is also anisotropic. We attribute this enhancement and anisotropy to the asymmetric Rashba contributions driven by an unbalanced spin accumulation at the differently hybridized top and bottom graphene interfaces, as highlighted by ad-hoc first-principles theory. The improvement in spin-to-charge conversion as well as its anisotropy reveals the importance of interfaces in hybrid 2D-thin film systems opening up new possibilities for engineering spin conversion in 2D materials, leading to potential advances in memory, logic applications, or unconventional computing.