Spin valve effect in VN/GaN/VN van der Waals heterostructures

Nitride-based van der Waals magnetic heterostructures can simultaneously utilize both charge and spin degrees of electrons, which are important materials for low-dimensional spintronic devices. In this work, we study the stabilities and the electronic and magnetic properties of GaN/VN and VN/GaN/VN van der Waals heterostructures via first-principles calculations. The GaN/VN van der Waals heterostructure is a half-metal with 100% spin polarization, which can be applied in a spin filter and spin injection. Although monolayer GaN is a nonmagnetic semiconductor, it can introduce half-metallic characters via the magnetic proximity effect in both GaN/VN and VN/GaN/VN van der Waals heterostructures. The easy magnetization axis of hexagonal VN transits from the out-of-plane to the in-plane direction after combining with hexagonal GaN due to the different orbital occupations. Moreover, the electronic properties of the VN/GaN/VN van der Waals heterostructure depend largely on the magnetic configurations of the VN layers. By applying parallel or antiparallel magnetic configurations, the VN/GaN/VN van der Waals heterostructure presents half-metallic and semiconducting characters. The transformation indicates that the VN/GaN/VN van der Waals heterostructure is a promising candidate for room-temperature van der Waals spin valve devices.