Nanosecond spin relaxation times in single layer graphene spin valves with hexagonal boron nitride tunnel barriers

TL;DR

This study demonstrates that using hexagonal boron nitride as a tunnel barrier in graphene spin valves enables room temperature spin relaxation times exceeding one nanosecond, confirming h-BN's effectiveness for spin injection.

Contribution

It provides experimental evidence that few-layer h-BN barriers improve spin relaxation times and non-local spin signals in graphene devices, addressing previous limitations.

Findings

Room temperature spin lifetimes >1 nanosecond in graphene with h-BN barriers

Few-layer h-BN yields better spin signals than monolayer h-BN

Confirmation that h-BN is an effective barrier for spin injection

Abstract

We present an experimental study of spin transport in single layer graphene using atomic sheets of hexagonal boron nitride (h-BN) as a tunnel barrier for spin injection. While h-BN is expected to be favorable for spin injection, previous experimental studies have been unable to achieve spin relaxation times in the nanosecond regime, suggesting potential problems originating from the contacts. Here, we investigate spin relaxation in graphene spin valves with h-BN barriers and observe room temperature spin lifetimes in excess of a nanosecond, which provides experimental confirmation that h-BN is indeed a good barrier material for spin injection into graphene. By carrying out measurements with different thicknesses of h-BN, we show that few layer h-BN is a better choice than monolayer for achieving high non-local spin signals and longer spin relaxation times in graphene.