Two-dimensional multiferroic materials are highly sought after due to their huge potential for applications in nanoelectronic and spintronic devices. Here, we predict, based on first-principle calculations, a single phase {\it triferroic} where three ferroic orders; ferromagnetism, ferroelectricity and ferroelasticity, coexist simultaneously in hole doped GdCl2 monolayer (a ferromagnetic semiconductor). This is achieved by substituting 1/3rd of the Gd2+ ions with Eu2+ in the hexagonal structure of GdCl2 monolayer. The resulting metallic state undergoes a bond-centered charge ordering driving a distortion in the hexagonal structure making it semiconducting again and {\it ferroelastic}. Further, the lattice distortion accompanied by a breaking of the lattice centrosymmetry renders a non-centrosymmetric charge distribution which makes the monolayer {\it ferroelectric}, at the same time. The two ferroic orders, ferroelectricity and ferroelasticity, present in Eu doped GdCl2 monolayer are found to be strongly coupled making it a promising candidate for device applications. The doped monolayer remains a ferromagnetic semiconductor with large 4f magnetic moment just like the parent monolayer and possesses an even higher (out-of-plane) magnetic anisotropy energy (MAE) than its pristine counterpart as desired for two dimensional magnets to have high transition temperature.
@article{arxiv.2211.02398,
title = {Two-dimensional Rare-earth Halide Based Single Phase Triferroic},
author = {Srishti Bhardwaj and T. Maitra},
journal= {arXiv preprint arXiv:2211.02398},
year = {2022}
}