Intrinsic triferroicity in a two-dimensional lattice

Abstract

Intrinsic triferroicity is essential and highly sought for novel device applications, such as high-density multistate data storage. So far, the intrinsic triferroicity has only been discussed in three-dimensional systems. Herein on the basis of first principles, we report the intrinsic triferroicity in a two-dimensional lattice. Being exfoliatable from the layered bulk, single-layer $\mathrm{Fe}{\mathrm{O}}_{2}\mathrm{H}$ is shown to be an intrinsically triferroic semiconductor, presenting antiferromagnetism, ferroelasticity, and ferroelectricity simultaneously. Moreover, the directional control of its ferroelectric polarization is achievable by 90 \ifmmode^\circ\else\textdegree\fi{} reversible ferroelastic switching. In addition, single-layer $\mathrm{Fe}{\mathrm{O}}_{2}\mathrm{H}$ is identified to harbor in-plane piezoelectric effect. The unveiled phenomena and mechanism of triferroics in this two-dimensional system not only broaden the scientific and technological impact of triferroics but also enable a wide range of nanodevice applications.