▎ 摘　　要

Graphene lateral spin valves (LSVs) are promising devices for future memory and magnetic field sensing applications. In this article, we study the dependence of the nonlocal spin resistance, R-NL, and the baseline resistance, R-BS, as a function of the graphene channel width, W. The scaling trend is quantitatively assessed by using graphene deposited by chemical vapor deposition, which provides a large number of devices with consistent performance. AsWis scaled from10 to 0.5 mu m, the change in R-NL matches the theory of contact-induced spin relaxation with a current spin polarization of 3%-5% and a spin diffusion length of lambda(s) = 1.5-2.5 mu m. We also observe a systematic and dramatic decrease in R-BS, which we attribute to the reduction in charge current spreading. However, we find in the narrowest devices that a small R-BS remains that arises due to thermoelectric effects, and this trend is confirmed using gate voltage- and charge current-dependentanalyses. Finally, we introduce a nonideality factor, m = vertical bar R-BS/R-NL vertical bar, as a figure of merit to describe the suppression of the baseline relative to the spin signal. In an LSV with L = 1.5 mu m, W = 0.5 mu m, and n- type conduction, the nonideality factor is as low asm = 0.0252 +/- 0.0202 at room temperature showing that nearly ideal bipolar and symmetric spin signals can be achieved in graphene LSVs.