Proximity induced room-temperature ferromagnetism in graphene probed with spin currents

TL;DR

This paper demonstrates room-temperature ferromagnetism in graphene induced by proximity to a ferromagnetic insulator, with direct measurement of exchange interaction and control of spin currents, advancing spintronic device potential.

Contribution

It provides the first direct measurement of exchange interaction in room-temperature ferromagnetic graphene via spin transport analysis.

Findings

Exchange field of approximately 0.2 T measured in graphene.

Proximity-induced ferromagnetism modulates spin currents effectively.

Demonstrates potential for magnetic-gate tunable spintronic devices.

Abstract

The introduction and control of ferromagnetism in graphene opens up a range of new directions for fundamental and applied studies. Several approaches have been pursued so far, such as introduction of defects, functionalization with adatoms, and shaping of graphene into nanoribbons with well-defined zigzag edges. A more robust and less invasive method utilizes the introduction of an exchange interaction by a ferromagnetic insulator in proximity with graphene. Here we present a direct measurement of the exchange interaction in room temperature ferromagnetic graphene. We study the spin transport in exfoliated graphene on a yttrium-iron-garnet substrate where the observed spin precession clearly indicates the presence and strength of an exchange field that is an unambiguous evidence of induced ferromagnetism. We describe the results with a modified Bloch diffusion equation and extract an average exchange field of the order of 0.2 T. Further, we demonstrate that a proximity induced 2D ferromagnet can efficiently modulate a spin current by controlling the direction of the exchange field. These results can create a building block for magnetic-gate tuneable spin transport in one-atom-thick spintronic devices.