Large Magnetoresistance and Efficient Spin Injection in Ferromagnet/Graphene/Fe3GeTe2 Van der Waals Magnetic Tunnel Junctions

The recent discovery of magnetic ordering in two-dimensional (2D) offers unprecedented opportunities to explore novel physics and device concepts in vdW magnetic tunnel junctions (MTJs). Here, using ab initio quantum transport calculations, we investigate the spin-dependent electronic transport across vdW MTJs composed of the Ni(111) electrodes and a graphene or graphene/Fe3GeT2/graphene spacer layer. We find that the relative magnetic orientations of Ni electrodes and the Fe3GeTe2 can dramatically affect the junction's low-bias transport properties. Interestingly, the graphene/Fe3GeTe2/graphene junction is shown to have perfect spin filtering and tunneling magnetoresistance (TMR) over 500%, which is 1 order higher than that of the graphene-based one. Such a giant TMR effect is driven by efficient orbital matching between electrodes and the Fe3GeTe2 space layer, depending sensitively on the magnetization direction of the Fe3GeTe2 layer. We also predict that the giant TMR effect is robust with respect to Fe3GeTe2 thickness and strain, which may vary in the experiment. This work highlights the feasibility of MTJs based on new 2D magnets in contact with conventional ferromagnetic electrodes.