Generation and Absorption of Pure Spin Currents Using Graphene Nonlocal Spin Valves

Abstract

This work describes the fabrication and measurement of nanoscale devices in which a spin-polarized electrical current is used to inject spins into graphene, which then diffuse. We demonstrate the electrical detection of spins in graphene devices with micron-scale spin diffusion lengths and analyze how the spin lifetime and spin diffusion lengths are affected by electrostatic gating. The spin current absorbed by an adjacent ferromagnet is calculated and demonstrated to increase as the electrical conductance of the graphene/ferromagnet interface is improved. Quantitative modeling, including a finite element model of the spatial distribution of spins and the effect of a thin metallic island, indicates that the absorbed spin current is nearing the regime necessary for future technological applications.