Two-dimensional (2D) ferroelectric materials have intrinsic polarized electric field, when they stack with other 2D materials to construct ferroelectric van der Waals heterostructures, they will produce a lot of novel properties, which has aroused extensive research interests. Therefore, based on first-principle calculations, we have comprehensively studied the electronic properties of LaBr2/& alpha;-In2Se3 ferroelectric heterostructures to investigate the reversibility and nonvolatility with information. Our calculations show that, the system is a ferromagnetic semiconductor with intrinsic valley polarization when & alpha;-In2Se3 is in the ferroelectric polarized up state. By switching the ferroelectric polarization of & alpha;-In2Se3, the heterostructure undergoes a transition from semi-conductor to half metal, which can be attributed to the competition between the built-in electric field (Eint) and & RARR; the polarized electric field Epi ,generated by the charge transfer at interface of heterostructure and the bound charge of & alpha;-In2Se3, respectively. Besides, the band arrangement types of LaBr2/& alpha;-In2Se3 heterostructure can be well modulated under extra electric filed and biaxial strain. Furthermore, we have observed valley-submerging under electric filed and strain, which indicates the valleytronic nature can also be on-off in LaBr2/& alpha;-In2Se3 heterostructures. More importantly, the realization of reversible and non-volatile properties depends on the intrinsic characteristics of heterostructure and does not require external mechanisms. Our research not only provides the possibility for the application of the LaBr2/& alpha;-In2Se3 heterostructures in nanodevices, but also give the theoretical support to the study of spintronics and valleytronics.

Spin polarized van der Waals (vdW) heterostructures have attracted considerable interest owing to the spin splitting manipulation. In this paper, first-principles calculations are employed to explore the two-dimensional arsenene/CrI3 vdW heterostructure as a promising spin polarized material, as well as the spin polarization under strain and electronic field are investigated. The most stable stacking configuration and ferromagnetic (FM) property of the arsenene/CrI3 vdW heterostructure have been confirmed. The detailed calculations show that the Curie temperature (Tc) of the FM coupling CrI3 layer in the heterostructure can be enhanced up to 61 K, which is attributed to both superexchange interaction and proximity exchange effect. The electronic structures suggest that this heterostructure possess an intrinsic type-II band alignment and diluted magnetic semiconductor property. Interestingly, we found a transition from diluted magnetic semiconductor to half-metal and gradually to metal induced by the biaxial strains, and the extra electronic field can modulate the "maxican hat" of the valance band maximum (VBM) of arsenene. Our work provides not only application prospects of the arsenene/CrI3 vdW heterostructure nanodevices but also theoretical effective support for the research and development of the spin electronics and flexible electronics. (c) 2022 Elsevier B.V. All rights reserved.