Two-dimensional vanadium tetrafluoride with antiferromagnetic ferroelasticity and bidirectional negative Poisson's ratio

Two-dimensional (2D) antiferromagnetic ferroelasticity and bidirectional auxeticity are highly sought for next-generation nanoelectronics, spintronics, or mechanical devices, but are rarely reported. Herein, using first-principles calculations, we report the coexistence of these intriguing properties in the vanadium tetrafluoride (VF4) monolayer. 2D VF4 is a direct wide-gap semiconductor with antiferromagnetic order stemming from the synergy between the direct exchange and superexchange of the d(xy) orbitals in adjacent V atoms. Notably, 2D VF4 features ferroelasticity with a moderate reversible strain and low transition barrier, enabling manipulation of the in-plane magnetic easy axis via external strain. Additionally, 2D VF4 simultaneously harbors an ultra-large negative Poisson's ratio (NPR) in both the in-plane and out-of-plane directions due to the hinged connection between the neighboring VF6 octahedra. Our work highlights a new material for the exploration of 2D multiferroic physics and the integration of antiferromagnetic ferroelasticity and large bidirectional auxeticity renders 2D VF4 a versatile candidate for the development of novel multifunctional devices.

Automated summary

In this study, the coexistence of 2D antiferromagnetic ferroelasticity and bidirectional auxeticity in vanadium tetrafluoride (VF4) monolayer was reported using first-principles calculations. The material features a wide-gap semiconductor with antiferromagnetic order, moderate reversible strain, and ultra-large negative Poisson's ratio (NPR), making it a versatile candidate for multifunctional devices in nanoelectronics, spintronics, and mechanical applications.