Lateral spin filter realized by monolayer Fe3GaTe2 and Fe3GaTe2/Graphene van der Waals heterostructures

Motivated by the lately discovered van der Waals ferromagnet Fe3GaTe2, a two-dimensional material with magnetic order and large perpendicular magnetic anisotropy above room temperature, we investigate two kinds of spin filters based on it. One is a flat pure Fe3GaTe2 monolayer and the other is a sandwich structure where the left and right parts are connected by a side-contacting graphene nanoribbon; both structures can be set in magnetic parallel or antiparallel configuration by external fields. Our first-principle calculation shows that the flat structure has large magnetoresistance (∼640 %) but relatively low spin filter efficiency (<50 %) at equilibrium, while the side-contacting structure shows a great enhancement in spin filter efficiency along with a relatively small magnetoresistance. Spin filter efficiency refers to the degree of spin polarization of the current passing through the device. For both structures, parallel configuration turns out to render a better filter than antiparallel configuration at equilibrium while the difference can be suppressed by applying a finite bias voltage. For side-contacting structure, different hybridization in different spins leads to very large spin filter efficiency (∼95.2 %) at equilibrium in parallel configuration, which may have a great potential in the application of future spintronics.