Large-scale BN tunnel barriers for graphene spintronics

TL;DR

This paper demonstrates scalable CVD-grown graphene spin-valve devices with h-BN tunnel barriers, showing that bilayer barriers enable efficient spin injection and reveal intrinsic spin relaxation times comparable to exfoliated graphene.

Contribution

It introduces a scalable CVD fabrication method for graphene spintronic devices using h-BN tunnel barriers, highlighting the effectiveness of bilayer barriers for spin injection.

Findings

Bilayer h-BN barriers enable efficient spin injection.

Spin relaxation time of 260 ps in CVD graphene.

Scalable CVD approach comparable to exfoliated graphene.

Abstract

We have fabricated graphene spin-valve devices utilizing scalable materials made from chemical vapor deposition (CVD). Both the spin-transporting graphene and the tunnel barrier material are CVD-grown. The tunnel barrier is realized by h-BN, used either as a monolayer or bilayer and placed over the graphene. Spin transport experiments were performed using ferromagnetic contacts deposited onto the barrier. We find that spin injection is still greatly suppressed in devices with a monolayer tunneling barrier due to resistance mismatch. This is, however, not the case for devices with bilayer barriers. For those devices, a spin relaxation time of 260 ps intrinsic to the CVD graphene material is deduced. This time scale is comparable to those reported for exfoliated graphene, suggesting that this CVD approach is promising for spintronic applications which require scalable materials.