Discovery of Intrinsic Ferromagnetic Ferroelectricity in Transition Metal Halides Monolayer

TL;DR

This paper reports the discovery of two-dimensional ferromagnetic ferroelectricity in layered transition metal halides, specifically in CrBr3 monolayers, revealing new multiferroic properties with potential nano-device applications.

Contribution

It demonstrates for the first time 2D ferromagnetic ferroelectricity in transition metal halides using first-principles calculations, highlighting the role of orbital and charge ordering.

Findings

CrBr3 monolayer exhibits in-plane multiferroicity

Charged (CrBr3)2Li is a ferromagnetic ferroelectric multiferroic

Mechanism involves asymmetric Jahn-Teller distortions

Abstract

The realization of multiferroics in nanostructures, combined with a large electric dipole and ferromagnetic ordering, could lead to new applications, such as high-density multi-state data storage. Although multiferroics have been broadly studied for decades, ferromagnetic ferroelectricity is rarely explored, especially in two-dimensional (2D) systems. Here we report the discovery of 2D ferromagnetic ferroelectricity in layered transition metal halide systems. On the basis of first-principles calculations, we reveal that charged CrBr3 monolayer exhibits in-plane multiferroicity, which is ensured by the combination of orbital and charge ordering as realized by the asymmetric Jahn-Teller distortions of octahedral Cr-Br6 units. As an example, we further show that (CrBr3)2Li is a ferromagnetic ferroelectric multiferroic. The explored phenomena and mechanism of multiferroics in this 2D system are not only useful for fundamental research in multiferroics but also enable a wide range of applications in nano-devices.