Intrinsic multiferroicity in two-dimensional VOCl2 monolayers

Abstract

The coexistence of ferroelectricity and magnetism in two-dimensional (2D) multiferroic materials with the thickness of few atomic layers offers a tantalizing potential for high-density multistate data storage but has been rarely verified in experiments. Herein, we propose a realistic 2D multiferroic material, VOCl₂ monolayer, which is mechanically strippable from the bulk material. It has a large intrinsic in-plane spontaneous electric polarization of 312 pC m⁻¹ and stable antiferromagnetism with the Néel temperature of 177 K. The off-center displacement of V ions that contributes to the ferroelectricity can be ascribed to the pseudo Jahn–Teller distortion. The energy barrier (0.18 eV) between two ferroelectric states with opposite electronic polarization renders the thermodynamic stability of the ferroelectricity and the switchability of the electric polarizations. The interplay between electric polarization and magnetism would lead to tunable ferroelectricity. Our findings are expected to offer a realistic platform for the study of 2D multiferroic materials as well as their applications in miniaturized memory devices.