Nonvolatile Electrical Control and Reversible Gas Capture by Ferroelectric Polarization Switching in 2D FeI₂/In₂S₃ van der Waals Heterostructures

Nonvolatile electrical control is the core of future magnetoelectric nanodevices. In this work, we systematically explore both the electronic structures and transport properties of multiferroic van der Waals (vdW) heterostructures consisting of a ferromagnetic FeI₂ monolayer and a ferroelectric In₂S₃ monolayer using density functional theory and the nonequilibrium Green’s function method. The results reveal that the FeI₂ monolayer can be reversibly switched between semiconducting and half-metallic properties by nonvolatile control of the In₂S₃ ferroelectric polarization states. Correspondingly, the proof-of-concept two-probe nanodevice based on the FeI₂/In₂S₃ vdW heterostructure exhibits a significant valving effect by modulating the ferroelectric switching. Moreover, it is also found that the preference of nitrogen-containing gases such as NH₃, NO, and NO₂ for adsorption on the surface of FeI₂/In₂S₃ vdW heterostructures strongly depends on the polarization direction of the ferroelectric layer. In particular, the FeI₂/In₂S₃ heterostructure shows reversible capture behavior for NH₃. As a result, the FeI₂/In₂S₃ vdW heterostructure-based gas sensor demonstrates high selectivity and sensitivity. These findings may open up a new route for the application of multiferroic heterostructures to spintronics, nonvolatile memories, and gas sensors.