Spin-polarized transport properties in magnetic moiré superlattices

Since the discovery of the fascinating properties in magic-angle graphene, the exploration of moire systems in other two-dimensional materials has garnered significant attention and given rise to a field known as "moire physics." Within this realm, the magnetic van der Waals heterostructure and the magnetic proximity effect in moire superlattices have also become subjects of great interest. However, the spin-polarized transport property in these moire structures is still a problem to be explored. Here, we investigate the spin-polarized transport properties in a moire superlattice formed by a two-dimensional ferromagnet CrI3 stacked on a monolayer BAs, where the spin degeneracy is lifted because of the magnetic proximity effect associated with the moire superlattices. We find that the conductance exhibits spin-resolved miniband transport properties at a small twist angle because of the periodic moire superlattices. When the incident energy is in the spin-resolved minigaps, the available states are spin polarized, thus providing a spin-polarized current from the superlattice. Moreover, only a finite number of moire period is required to obtain a net spin polarization of 100%. In addition, the interlayer distance of the heterojunction is also moire modifiable, so a perpendicular electric field can be applied to modulate the direction of the spin polarization. Our finding points to an opportunity to realize spin functionalities in magnetic moire superlattices.