Room-temperature spin-lifetime anisotropy exceeding 60 in bilayer graphene spin valves proximity coupled to WSe$_2$

TL;DR

This study demonstrates that proximity coupling bilayer graphene with WSe₂ at room temperature results in a spin lifetime anisotropy exceeding 60, with significant implications for spintronic applications due to preserved charge mobility.

Contribution

It provides the first room-temperature measurement of high spin lifetime anisotropy in bilayer graphene coupled with WSe₂, highlighting a novel approach to spin manipulation.

Findings

Spin lifetime anisotropy exceeds 60 at room temperature.

Out-of-plane spin lifetime is about 250 ps, unaffected by WSe₂.

In-plane spin lifetime is less than 4 ps, suppressing in-plane spin signals.

Abstract

A spin lifetime anisotropy between in-plane and out-of-plane spins in bilayer graphene (BLG) can be achieved by spin-orbit proximity coupling of graphene to transition metal dichalcogenides. This coupling reduces the in-plane spin lifetime due to proximity-induced spin scattering, while the out-of-plane spin lifetime remains largely unaffected. We show that at room temperature spin lifetime anisotropy exceeds 60 in a bilayer graphene lateral spin valve proximity coupled to WSe$_2$. The out-of-plane spin lifetime of about 250 ps closely matches that of a BLG reference region not in contact with WSe$_2$. In contrast, the estimated in-plane spin lifetime of less than 4 ps leads to a complete suppression of the in-plane spin signal at the ferromagnetic Co/MgO spin detector. The proximity coupling of WSe$_2$ to BLG is particularly promising, as it does not compromise the charge carrier mobility within the graphene channel.