CVD bilayer graphene spin valves with 26 $\mu$m spin diffusion length at room temperature

TL;DR

This study demonstrates that CVD-grown bilayer graphene spin valves can achieve a spin diffusion length of 26 μm at room temperature, matching the performance of exfoliated graphene, through improved fabrication techniques.

Contribution

The paper introduces a full-dry transfer method for CVD bilayer graphene spin valves, significantly enhancing device performance and spin transport properties at room temperature.

Findings

Spin lifetime up to 5.8 ns at room temperature

Spin diffusion length of 26 μm at room temperature

Charge carrier mobility of approximately 24,000 cm²/(V·s)

Abstract

We present inverted spin-valves fabricated from CVD-grown bilayer graphene (BLG) that show more than a doubling in device performance at room temperature compared to state-of-the art bilayer graphene spin-valves. This is made possible by a PDMS droplet-assisted full-dry transfer technique that compensates for previous process drawbacks in device fabrication. Gate-dependent Hanle measurements show spin lifetimes of up to 5.8 ns and a spin diffusion length of up to 26 $\mu$m at room temperature combined with a charge carrier mobility of $\approx$ 24 000 cm$^{2}$(Vs)$^{-1}$ for the best device. Our results demonstrate that CVD-grown BLG shows equally good room temperature spin transport properties as both CVD-graphene and even exfoliated single-layer graphene.