Magnetized graphene is a promising candidate for spintronic devices, where half-semimetallic or -semiconducting property is highly desirable. Using first-principles calculations, we show that stable ferromagnetic ordering can exist readily in non-compensated bonding BN/graphene bilayer with triangular defects (TDs) by analogizing with bonding BN/BN bilayer observed in experiment. More intriguingly, regardless of the non-compensated defect states in the gap, such spin-polarized BN/graphene bilayer exhibits spin-gapless and -gapped semiconducting band structures with quadratic and linear dispersion, respectively, depending on the size of TDs. The massive or massless electronic states of bonding BN/graphene are associated with the electron localization degree at the zigzag edges of TDs. Our findings might provide another feasible strategy to realize stable magnetized graphene and engineer its electronic and magnetic features.

Graphene based p-n junctions exhibit intriguing and distinctive electronic properties, making them promising candidates for spintronic and spin photonic devices. While the attendant realization of magnetized graphene p-n junctions is highly desirable. Using first-principles calculations, we show that in the presence of magnetic proximity coupling effect of graphene supported on Te-termination magnetic Janus VSeTe monolayer (VSeTe/G), the graphene is readily spin-polarized and the Dirac bands near Fermi level keep intact. More interestingly, the external electric field (Eex) could significantly influence the bands of the spin down channel near Fermi level, due to the dominant electronic Coulomb screening effect. When the Eex exceeds 0.35eV/Å with opposite direction to intrinsic dipole moment, the VSeTe/G heterostructure would turn into n type doping from the initial light p type doping in the spin down channel. However, those of the spin up channel in the vicinity of Fermi level are inert and still preserve initial p type against external electric field. In terms of such distinctive differences between the Dirac bands in the spin up and spin down channels, we propose a featured spin resolved graphene p-n junctions on magnetic Janus VSeTe by applying appropriate external electric field. Our findings are generally applicable to other similar magnetic Janus systems (i.e., graphene/FeICl) and might provide a feasible strategy to realize stable spin resolved graphene p-n junctions extendedly.

Nonmagnetic graphene-based van der Waals heterotrilayers exhibit peculiar electronic features such as energetically and/or spatially resolved Dirac rings/cones. Here, using first-principles calculations we study the effect of magnetic proximity effect and mirror symmetry of antiferromagnetic CrAs 2 monolayer sandwiched between graphene on the Dirac cones. We clearly identify the common vertical shift of the Dirac bands in the spin up channel. While in the spin down channel, we surprisingly observe the remarkable transverse splitting Dirac cones. The underling mechanism can be attributed to the static electric field caused by the charge transfer between the interlayers, and the polarized field arising from the weakly magnetized graphene. Both fields collectively give rise to an inequivalent space inversion broken between graphene and CrAs 2 layers. Such unique Dirac states are absent in its nonmagnetic or ferromagnetic counterpart, ferromagnetic heterotrilayer with the glide symmetry, and graphene/CrAs 2 heterobilayer. Our findings would provide a new insight into the correlation between Dirac cones and magnetic monolayer sandwiched between graphene.