Proximity induced room temperature ferromagnetism in graphene probed with spin currents

We present a direct measurement of the exchange interaction in room temperature ferromagnetic graphene. We study the spin transport in exfoliated graphene on an 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 findings can create a building block for magnetic-gate tuneable spin transport in one-atom-thick spintronic devices. (paper)