Twist dependent spin resolved conductance in Graphene|hBN van der Waals heterostructure

Graphene-hexagonal boron nitride van der Waals heterostructures are close to ideal systems for nanoelectronic and spintronic applications. In particular, such heterostructures are considered ideal for achieving high spin accumulations in graphene, an unprecedented material for efficient spin communication. In this paper, we unravel how the efficiency of spin injected charge carriers have changed by twisting the h-BN barrier interfacing with graphene and Ferromagnetic lead of Ni(111)/Co(111). Through First-principles calculations, we show that spin-up and spin-down electrons exhibit remarkably distinct conductivities leading to a high modulation of spin injection in both magnitude and sign as orientation changes. Our results suggest that for nanoscopic contacts, the magnitude and sign of spin injection efficiency are highly dependent upon twists between graphene and h-BN lattices and it is possible to reach a high ~67%, even utilizing single-layer hexagonal boron nitride by manipulating the angle between graphene and hexagonal boron nitride. Most negative spin polarization ~`90% is achieved due to trilayer of hBN using Co(111) electrode. Our calculations provide a guideline to engineer van der Waals heterostructure for efficient future spintronic devices.