Ferroelectric control of half-metallicity in A-type antiferromagnetic GdI2 bilayer coupled with ferroelectric In2Se3

A-type antiferromagnetic half-metal has great application potential in memory and spintronic devices. GdI2 bilayer is an A-type antiferromagnet with intralayer ferromagnetic coupling and interlayer antiferromagnetic coupling. Under an electric field, the spin degeneracy of the GdI2 bilayer is broken. As an electric field exceeds the critical electric field of 0.08 V/Å, the GdI2 bilayer exhibits antiferromagnetic half-metallicity. The bi-GdI2/In2Se3 heterojunction achieves the transition for GdI2 bilayer from semiconductor to half-metal and the ferroelectric memory can be achieved. The In2Se3/bi-GdI2/In2Se3 heterojunction realizes the switching of the spin direction of the half-metal for GdI2 bilayer and the spin field effect transistors can be achieved. The bi-GdI2/bi-In2Se3 heterojunction achieves functions similar to the bi-GdI2/In2Se3 heterojunction. The band transition mechanism of these heterojunctions is mainly caused by the charge transfer at the GdI2 and In2Se3 interfaces and the polarization field of In2Se3. The construction of heterojunction and biaxial strain can significantly regulate the magnetic anisotropy energy (MAE). The tensile strain increases the total MAE, while the compressive strain decreases the total MAE. The heterojunctions under biaxial strain always keep the easy magnetization axis in the xy plane. Based on the GdI2 bilayer, applying an electric field or constructing a van der Waals heterojunction can achieve antiferromagnetic half-metal.