A two-dimensional ferroelectric ferromagnetic half semiconductor in a VOF monolayer

Abstract

Two-dimensional multiferroic materials have attracted great attention owing to their promising prospects for miniaturized electronic and memory devices. Here, we propose a highly stable 2D multiferroic VOF monolayer which is an intrinsic ferromagnetic half semiconductor with large spin polarization ∼2 μ_B/V and significant uniaxial magnetic anisotropy along the a-axis (410 μeV/V). Meanwhile, it shows excellent ferroelectricity with a large spontaneous polarization of 32.7 μC cm⁻² and a moderate energy barrier (∼43 meV per atom) between two ferroelectric states, which can be ascribed to the Jahn–Teller distortions. Moreover, the VOF monolayer harbors an ultra-large negative Poisson's ratio in the in-plane direction (∼−0.34). The Curie temperature evaluated from Monte Carlo simulations based on the Ising model is about 215 K, which can be further enhanced to room temperature by 4% compressive biaxial strain. The combination of ferromagnetism and ferroelectricity in the VOF monolayer could provide a promising platform for future study of multiferroic effects and next-generation multifunctional nanoelectronic device applications.