Oblique spin injection to graphene via geometry controlled magnetic nanowires

TL;DR

This paper demonstrates a geometry-based method to induce and measure out-of-plane spin polarization in graphene using magnetic nanowires, enabling vector magnetometry in 2D spintronic devices.

Contribution

The study introduces a novel geometric approach to control and quantify out-of-plane spin polarization in graphene via magnetic nanowires.

Findings

Observation of both switching and spin precession phenomena.

Quantification of the spin polarization angle.

Correlation of the polarization angle with nanowire geometry.

Abstract

We exploit the geometry of magnetic nanowires, which define 1D contacts to an encapsulated graphene channel, to introduce an out-of-plane component in the polarisation of spin carriers. By design, the magnetic nanowires traverse the angled sides of the 2D material heterostructure. Consequently, the easy axis of the nanowires is inclined, and so the local magnetisation is oblique at the injection point. As a result, when performing non-local spin valve measurements we simultaneously observe both switching and spin precession phenomena, implying the spin population possesses both in-plane and out-of-plane polarisation components. By comparing the relative magnitudes of these components, we quantify the angle of the total spin polarisation vector. The extracted angle is consistent with the angle of the nanowire at the graphene interface, evidencing that the effect is a consequence of the device geometry. This simple method of spin-based vector magnetometry provides an alternative technique to define the spin polarisation in 2D spintronic devices.