Giant and Anisotropic Enhancement of Spin-Charge Conversion in Graphene-Based Quantum System

Abstract

The ever-increasing demand for efficient data storage and processing has fueled the search for novel memory devices. By exploiting the spin-to-charge conversion phenomena, spintronics promises faster and low power solutions alternative to conventional electronics. In this work, a remarkable 34-fold increase in spin-to-charge current conversion is demonstrated when incorporating a 2D epitaxial graphene monolayer between iron and platinum layers by exploring spin-pumping on-chip devices. Furthermore, it is found that the spin conversion is also anisotropic. This enhancement and anisotropy is attributed 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.