Sliding multiferrocity in van der Waals layered CrI$_2$
Abstract
Understanding magnetoelectric coupling in emerging van der Waals multiferroics is crucial for developing atomically thin spintronic devices. Here, we present a comprehensive first-principles investigation of magnetoelectric coupling in orthorhombic CrI. Monte Carlo simulations based on DFT-calculated magnetic exchange interactions suggest a proper-screw helimagnetic ground state with a N\'{e}el temperature consistent with experimental observations. A ferroelectric switching pathway driven by interlayer sliding is predicted, featuring a low switching energy barrier and out-of-plane ferroelectric polarization. To quantitatively characterize the magnetoelectric effect in orthorhombic CrI and its microscopic origin, we evaluate the spin-driven polarization using the paramagnetic phase as a reference alongside the magnetoelectric tensor method. The extracted spin-driven polarization aligns along the -axis, with its origin dominated by the exchange-striction mechanism. Although in-plane components of the total polarization in the bulk vanish due to global symmetry constraints, each CrI single layer exhibits local electric polarization along the direction, arising from the generalized spin-current mechanism, which couples spin chirality to the electric polarization. As a result, we further predict that a proper-screw helimagnetic state may persist in monolayer CrI, with its charity reversable by switching the in-plane electric polarization through applying external electric field, providing another promising candidate for electrical control of two-dimensional multiferroics.
Cite
@article{arxiv.2507.17562,
title = {Sliding multiferrocity in van der Waals layered CrI$_2$},
author = {Hui-Shi Yu and Xiao-Sheng Ni and Kun Cao},
journal= {arXiv preprint arXiv:2507.17562},
year = {2026}
}