Spin transport in fully hexagonal boron nitride encapsulated graphene

TL;DR

This study demonstrates room-temperature spin transport over 12.5 micrometers in fully hBN-encapsulated graphene devices, highlighting the benefits of encapsulation and hBN tunnel barriers for spintronic applications.

Contribution

It introduces a fully hBN-encapsulated graphene spin valve with a novel device structure that achieves long-distance spin transport at room temperature.

Findings

Spin transport over 12.5 micrometers at room temperature.

Homogeneous charge and spin transport due to full encapsulation.

Efficient spin injection despite conductivity mismatch.

Abstract

We study fully hexagonal boron nitride (hBN)-encapsulated graphene spin valve devices at room temperature. The device consists of a graphene channel encapsulated between two crystalline hBN flakes; thick-hBN flake as a bottom gate dielectric substrate which masks the charge impurities from SiO2/Si substrate and single-layer thin-hBN flake as a tunnel barrier. Full encapsulation prevents the graphene from coming in contact with any polymer/chemical during the lithography and thus gives homogeneous charge and spin transport properties across different regions of the encapsulated graphene. Further, even with the multiple electrodes in between the injection and the detection electrodes which are in conductivity mismatch regime, we observe spin transport over 12.5 um long distance under the thin-hBN encapsulated graphene channel, demonstrating the clean interface and the pin-hole free nature of the thin-hBN as an efficient tunnel barrier.