The mechanisms are revealed and analyzed by the connection of these effects to the evolution of the spin-resolved electron transmission spectra and pathways around the Fermi level at zero bias. The maximum of spin filtering efficiency can be up to 99%. WTe 2 in its bulk form has an indirect band gap but nanoribbons and nanosheets of WTe 2 have direct band gaps. WTe 2 nanoribbons can be categorized depending on the edge structure in two types: armchair and zigzag. It has a much lower electron mobility than graphene, but its around 3-5 times higher than MoS 2 and about 3 times higher than silicon and so this is a promising material. We have investigated the electronic properties of WTe 2 armchair nanoribbons with defects. The researcher produced phosphorene and started studying it. In addition, the effects of spin-filtering and negative differential resistance are also observed in those heterojunctions. Graphene in its basic form is a superconductor and so is less suited to make transistors. Specifically, the magnetoresistance ratio can be up to 10 4% for graphene/γ-graphyne heterojunction, but only 300% for the graphene/(6,6,12)-graphyne one. Our important result here is that these heterojunctions can exhibit an interesting variation of magnetoresistane by applying ferromagnetic stripes or external magnetic fields onto the ribbons to initially orient their spin configuration. To this end, we study the spin-charge transport properties for monolayer graphene/graphyne zigzag-edged nanoribbon heterojunctions by employing the ab initio calculations, where two types of γ- and (6,6,12)-graphynes are considered, respectively. Recently, considering these 2D carbon allotropes have similar bond lengths and unit cell shapes, ensuring a perfectly matched interface between them and construction of graphene/graphyne heterojunctions feasible. Graphene and graphyne hold great potential for spintronic device applications due to their exceptionally good electrical and mechanical properties in the pristine form.